The Phrasal Verb 'Fill In' Explained
- Phrasal Verbs Explained
- Jan 26, 2024
- 9 min read
Updated: Jul 12
An explanation of the different meanings of the English phrasal verb 'fill in' from a native speaker, with lots of examples in context

Hello and welcome to my website for English learners all about phrasal verbs where I explain their different meanings to help you understand, learn and use them like a native.
'Fill in' is an English phrasal verb with a variety of meanings that all, in some way, mean to fill a kind of empty space, whether that be a physical hole or a gap in a person's knowledge of a situation. In this post, I will look at all of these meanings and how they are used in English by native speakers, with plenty of examples to aid your understanding. So, without further ado, let's get started....
TABLE OF CONTENTS (Click to jump to each one)
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THE BASICS
FILL IN: KEY INFORMATION
Usage | Common |
Number of meanings | 6 |
Past tense forms | Filled in / Filled in |
Separable? | Yes |
In order to better understand the meanings of the phrasal verb 'fill in', let's first take a look at the meanings of the individual words 'fill' and 'in'.
The verb 'to fill' is a fairly common verb in English, which carries a general meaning of causing something that is empty, or partially empty, to become full. In addition to this, the verb 'to fill' is used a lot in different phrasal verb constructions such as 'fill out', 'fill up' and 'fill in'. Unlike many other English verbs, 'to fill' does not have multiple, diverse meanings and most of the time the idea it conveys is 'to make something full',
The prepositional particle 'in' is a common feature in phrasal verbs and has a general meaning of being in an internal space when used as a preposition and movement towards an internal space when used as an adverb. This adverbial usage of motion towards an internal space is often transferred into phrasal verb constructions and meanings.
So, now that we have covered the basics, let's take a look at the meanings of 'fill in'...
MEANING 1: To complete a form

CEFR Language Level | A2 - Elementary |
Usage | Common |
Where is it used? | British English |
Potential synonyms | To fill out, to complete |
Separable? | Yes |
If you have ever gone to an English speaking country for a period of time, it is likely that you will have completed a document or a form with your information. Furthermore, if you were coming to the UK, it is likely that you have may have been asked to 'fill in' this document. That is because 'to fill in' means to complete a form or document by giving the requested information in the necessary gaps.
Nouns commonly used with this application....
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The idea of this first usage can be linked directly back to the meaning of 'to fill' as it literally means to make the gaps (or empty spaces) on the form or document full by writing 'in' the details.
Fill in or fill out?
Confusingly, in English the phrasal verb 'fill out' also means the exact same thing and is interchangeable with the phrasal verb 'fill in'. Whilst there is no real difference in the meanings between these two, you should know that 'fill out' is the version that is favoured in American English and 'fill in' is more of a British usage. With that being said however, 'fill out' sounds perfectly natural to my ears as a native speaker of British English and it is also used here all the time.
As you can imagine, 'fill in' is commonly used with such nouns as 'form', 'document', 'application' and 'section', i.e. words for documents that require informational input. Grammatically, it is separable and the direct object (e.g. form or document) can happily go in the middle of the phrasal verb or after it with no discernible change of meaning.
Before you reach British passport control in the airport, you need to fill this form in.
If you haven't filled in the survey on our website yet, please go online before your next appointment and do so.
John realised that he had filled in all of the wrong sections of his tax return form and had to start it again.
Fill in this job application and send it to the company by Monday.
MEANING 2: To fill a hole or gap

CEFR Language Level | B1 - Intermediate |
Usage | Medium |
Where is it used? | Everywhere |
Potential synonyms | To fill |
Separable? | Yes |
In the last section, we looked at how 'fill in' is used to talk about completing the blank spaces on a form or document and for this second meaning we are keeping to the same idea, however this time we need to substitute the idea of blank spaces on paper with empty physical spaces such as holes, cracks and gaps.
Nouns commonly used with this application....
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For this usage of the phrasal verb 'fill in', we are therefore talking about moving material into a physical space to make it full or complete, often with the objective of having a level surface at the end of it. Typical examples of this would be filling in a hole in the ground with soil to make it even and filling in cracks in a wall with plaster to make it smooth. As you can probably guess, this usage of 'fill in' is used a lot when talking about DIY, building and physical work.
Like the previous usage, this meaning of 'fill in' is separable and the direct object (hole, gap etc.) can be placed between or after the phrasal verb. I would say however that native speakers naturally tend to place the object afterwards more often.
We removed a pond from our garden and filled in the hole with soil and compost.
After the earthquake there was a huge crack in my wall, which I have temporarily filled in with plaster whilst I decide what to do about it.
What is the best way to fill in drill holes in sheet metal?
MEANING 3: To fill empty spaces with colour

CEFR Language Level | B1 - Intermediate |
Usage | Medium |
Where is it used? | Everywhere |
Potential synonyms | To fill |
Separable? | Yes |
This next usage of 'fill in' is definitely one that you may have come across if you are a painter or artist of some sort. Again, for this third usage of 'fill in' we are staying with the idea of filling an empty space and this time it is not with written words or physical material but with colour.
With this meaning, if you have a drawing, painting or design and you fill an uncoloured part of it with colour, you 'fill it in', so that the part in question is no longer the same colour as the canvas or paper, but rather the colour that the artist has chosen as part of the artwork.
Outside of the artistic world, this can also be used for home decorating or, in fact, for anything where you add a colour to hitherto blank space. Interestingly, this is also common for tattoos and make-up, especially with lipstick for lips when you add lip liner around the edge of the lips and then fill in the rest with lipstick...I'm no expert in putting on make-up but I believe that this is the procedure. Either way, 'fill in' is definitely used with lipstick!
In order to draw the ladybird's wings, I drew black spots on them and filled the rest in with red.
Helen applied the lip liner around the outside of lips and then filled them in with lipstick.
For your tattoo, you will need to have two separate appointments with the tattoo artist; the first to draw the outline of the picture and the second to fill it in with colour.
MEANING 4: To give someone missing information

CEFR Language Level | C1 - Advanced |
Usage | Medium |
Where is it used? | Everywhere |
Potential synonyms | To inform |
Separable? | Yes |
If you have ever been in a situation where you do not have all of the information about it, you will probably need someone to 'fill you in'. This means that they give you the information that you are missing, so that you are fully informed about the situation at hand.
With this fourth meaning of 'fill in', we are still talking about making something full or complete but this time it is people, or more specifically, the gaps in people's knowledge about a specific matter. It is normally always used in dynamic situations where things change and develop, whether this be social or professional, and if a person is not present when these developments occur, they will not be aware of the latest information, for example when you go on holiday and take time off work. They will therefore have gaps in their knowledge and these will then need to be 'filled in'.
The additional preposition 'on' is often also required with this usage to specify the situation or circumstance in question (see the examples below). The preposition 'about' can also be used instead of 'on' but this is used slightly less. Grammatically, this usage is separable and this is how I believe it is used the majority of the time by native speakers.
John has just filled me in on everything that has happened since I went away on holiday. I can't believe it!
Has anyone told you the latest information or do you need me to fill you in?
Let's go out for a coffee and I can fill you in on the latest developments with my family.
Somebody needs to fill the manager in about what happened in the meeting yesterday when he was at the conference.
MEANING 5: To be a substitute for someone

CEFR Language Level | C1 - Advanced |
Usage | Medium |
Where is it used? | Everywhere |
Potential synonyms | To cover, to be a substitute for |
Separable? | No |
I am sure that you can all remember back to your school days when your normal teacher was sick or was not able to work and another temporary teacher was appointed to teach your class instead. You can say that this temporary teacher was 'filling in' for your regular teacher whilst he or she was absent and this is exactly the meaning of this next usage of the phrasal verb 'fill in'.
In a professional sense, if you 'fill in' for another person, it means that you do their job on a temporary basis as they are not able to do it for some reason. As with the example above, this is often used with substitute teachers but it can also be used for any type of job role where one person does another person's work for a short-term period. Here, we have the recurrent idea of filling a gap, which this time is a job role, albeit ad interim.
Grammatically, this usage of 'fill in' requires the additional preposition 'for' to specify the person or colleague who will temporarily be absent and replaced. Also, unlike the previous usages of 'fill in' that we have looked at, this one is not separable.
Roger is going on vacation next week, so I have to fill in for him and teach his senior classes.
Does anyone want to volunteer to fill in for Lisa whilst she is out of the office next week?
Martin is unfortunately off sick today, however Laura is filling in for him, so please contact her and she will assist you in his absence.
MEANING 6: To occupy your spare time

CEFR Language Level | C1 - Advanced |
Usage | Medium |
Where is it used? | Everywhere |
Potential synonyms | To pass time |
Separable? | No |
You may have realised by now that every single usage of 'fill in' that we have covered so far contains an idea of filling something that is empty.....and this final usage is no different! 😜
This last meaning of 'fill in' is 'to occupy your spare time by doing something unimportant or trivial'. Moreover, this is normally whilst you are waiting for something else to happen. For example, if you finish work at 5pm and have planned to meet a friend for a drink at 7pm, you will need to do something to occupy yourself for the two hours that you wait and we call this 'filling in' time. As you have probably guessed from the example, the empty thing that requires filling in with this usage is time.
My train arrives at 3pm this afternoon and my connecting train doesn't leave until 6pm, so I'll need to find something to do to fill in the time whilst I am waiting.
I had nothing to do until the evening, so I filled in the day playing computer games and drinking coffee.

We have now reached the end of this post and I just want to say thank you for clicking on my post and reading it. I hope that you've enjoyed it and have been able to learn something new about the phrasal verb 'fill in'. If you enjoyed this post, please go ahead and check out some of my other posts.
Now it is YOUR turn. Can you think of a sentence yourself using 'fill in'. Write it in the comments section below if you can, or alternatively any comments, suggestions or feedback that you may have....don't be shy!!!
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THE END
