fill in

Short definition: The phrase fill in means to complete missing information on a form, or to temporarily take someone’s place, depending on the situation.

Looking for a clear and natural explanation of the phrasal verb fill in? This expression is very common in everyday English and is often used when talking about completing missing information, temporarily replacing someone, or providing additional details so a situation becomes clearer. You might hear it in schools, offices, meetings, and casual conversations when someone needs to add information or step in to help when another person is unavailable. Because of this flexibility, fill in can describe both completing something and temporarily taking someone’s place. Below are detailed meanings with realistic examples so you can clearly understand how fill in works in everyday English.

fill in v. /ˌfɪl ˈɪn/

Forms: fill in, fills in, filled in, filling in
Related: complete v., substitute v., explain v., inform v.
Syllable: fill-in

  1. (Verb) To complete missing information in a document or form.

    To fill in most commonly means writing or adding information in empty spaces of a form, questionnaire, or document so that the information becomes complete.

    Please fill in your name and address on the application form.
    The teacher asked the students to fill in the missing answers in the worksheet.
    Make sure you carefully fill in every blank section before submitting the form.

    Synonyms: complete, enter details, write in, add information, supply answers, provide data, record information, write responses, insert details, complete fields, answer blanks, finish form
    Antonyms: leave blank, skip section, omit information, ignore form, erase entry, remove details, neglect fields, abandon form, discard document, forget to complete, overlook section, avoid answering

  2. (Verb) To temporarily replace someone who is absent.

    In another sense, fill in means temporarily doing someone else's job or role when they are unavailable or absent.

    She agreed to fill in for the manager while he was on vacation.
    A substitute teacher came to fill in for the regular instructor.
    He often fills in for his coworker during busy periods at the office.

    Synonyms: substitute, stand in, replace temporarily, cover for, step in, act as substitute, take over temporarily, serve as backup, assist temporarily, fill the role, take someone’s place, deputize
    Antonyms: step aside, withdraw, abandon role, resign, vacate position, leave duty, avoid responsibility, refuse replacement, step down, leave vacant, decline task, exit role

  3. (Verb) To provide additional details or explain something more clearly.

    Fill in can also mean giving someone extra information so they understand a situation, event, or conversation better.

    She filled me in on everything that happened during the meeting.
    Can you fill us in about what the manager decided yesterday?
    After the trip, he filled in his friends about the experience and what they missed.

    Synonyms: inform, update, explain, brief, report, describe events, bring up to date, share details, clarify situation, recount information, summarize events, give explanation
    Antonyms: conceal information, hide details, keep secret, mislead, confuse, obscure facts, suppress information, withhold details, distort story, disguise truth, misinform, avoid explanation

Conversation Using the Phrasal Verb Fill in

At a busy medical clinic, Sebastian and Elena are discussing an employee's absence. This dialogue explores fill in, which means to provide missing information on a document, or to do someone's job for a short time because they are away.

Sebastian: Since the receptionist is out sick today, do you think you could fill in for her and handle the phone calls this morning?

Elena: I’ll fill in as best as I can, but I’ll need someone to fill in the details of the new scheduling system for me first.

Sebastian: I read that it’s often difficult to find a qualified person to fill in for a specialized role like a surgeon or a pilot.

Elena: I noticed that you forgot to fill in your middle name on the insurance application form we submitted yesterday afternoon.

Sebastian: If you fill in the gaps in the story with your imagination, it becomes much more interesting for the children to listen to.

Elena: I saw a worker fill in the deep potholes on the street to make the road safer for the heavy trucks and cars passing by.

Sebastian: It’s helpful when a colleague can fill in the context of a meeting that you were unable to attend due to a prior commitment.

Elena: I agree; I’m going to fill in the background information on this report so that the board members have a clear picture of our progress.

Sebastian: I’m glad you could fill in today; your help has made the transition much smoother for everyone in the clinic.

Elena: No problem; once you fill in the final patient records, we can finish the shift and head home for the evening.

Phrases Containing the Phrasal Verb Fill In

The phrases below show how the phrasal verb fill in is used to talk about completing forms, providing missing information, or temporarily replacing someone.

Fill in the form

To complete a document with information.

Please fill in the form carefully and make sure all required fields are completed before submission.

Fill in the details

To provide missing information.

The manager asked us to fill in the details so the report would be more comprehensive and accurate.

Fill in for someone

To replace someone temporarily.

She agreed to fill in for her colleague who was on leave for a week.

Fill in the blanks

To complete missing words or data.

Students were instructed to fill in the blanks using the vocabulary provided in the box.

Fill in an application

To complete a job or program request.

He filled in an application for the scholarship and submitted it before the deadline.

Fill in the gaps

To supply missing parts.

The documentary helped fill in the gaps in our understanding of historical events.

Fill in missing information

To provide data that is not yet given.

Please fill in missing information so we can process your request without delays.

Fill in a report

To complete an official document.

The supervisor asked the staff to fill in a report after the inspection was completed.

Fill in temporarily

To replace for a short period.

He filled in temporarily while the regular instructor attended a conference abroad.

Fill in the questionnaire

To answer survey questions.

Participants were encouraged to fill in the questionnaire honestly to improve the service.

Fill in the space

To occupy an empty area.

They added decorative plants to fill in the space and make the room feel more welcoming.

Fill in the time

To spend time usefully.

While waiting for the train, she filled in the time by reading a short novel.

Fill in completely

To complete every section.

Make sure to fill in completely all sections of the contract before signing it.

Fill in your name

To write your name in a space.

Please fill in your name at the top of the page before handing in the test paper.

Fill in carefully

To complete something with attention.

She filled in the medical history form carefully to avoid misunderstandings.

Fill in online

To complete a digital form.

You can fill in the registration form online instead of visiting the office in person.

Fill in for the manager

To replace a supervisor temporarily.

He had to fill in for the manager during her business trip abroad.

Fill in additional information

To provide extra data.

Please fill in additional information if you have any special requirements.

Fill in missing data

To add absent statistics.

The analyst filled in missing data before finalizing the presentation slides.

Fill in the chart

To complete a table or graph.

Students were asked to fill in the chart using information from the reading passage.

Words Rhyme with fill in

bill in
drill in
grill in
hill in
kill in
pill in
quill in
skill in
still in
will in
in
bin
fin
pin
sin
tin
win
grin
spin
skin
thin
twin
begin
within
penguin
genuine
violin
discipline
bulletin
origin
POS: Verb Phrase