What does fill mean?
Fill is one of the most versatile and frequently used verbs in English. At its core it means to make something full — pouring water into a glass until no space remains, or loading a truck with boxes. From that concrete sense it extends naturally to time and space: music can fill a room, and work can fill a day. It also carries an abstract sense of satisfaction: you can fill a vacancy at a company, fill an order at a warehouse, or fill a need in a community. As a noun, fill names the amount required to make something full, or material used to plug a hole. The word appears constantly in fixed phrases such as 'fill in a form', 'fill a gap', and 'fill the bill', meaning to serve a purpose exactly. Because it spans physical, temporal, and abstract domains, fill is essential vocabulary for learners and native speakers alike.
To make full; to occupy or take up the whole of a space, container, or period of time; to fulfil or satisfy a need, requirement, or role.
"He filled the glass to the brim with cold water."
Common phrasal forms include 'fill in' (complete a form, or inform someone), 'fill out' (complete a form), and 'fill up' (make completely full).
An amount of something sufficient to make a container or space full; also, material used to fill a hole, gap, or cavity.
"The dentist placed a white composite fill in the cavity."
As a noun, 'fill' is less common than the verb and appears mainly in technical or specialized contexts such as dentistry, construction, and catering ('a fill of coffee').
The Old English ancestor of 'fill' — fyllan — simply meant 'to make full', making it one of those rare everyday verbs whose meaning has stayed essentially unchanged for over a thousand years.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of fill
Fill descends from the Old English verb fyllan, formed from the adjective full, meaning literally 'to make full'. This makes it part of a small family of causative verbs built from adjectives, alongside words like 'fell' (to make fall). Cognates appear across the Germanic languages, including Old Norse fylla and German füllen, all tracing back to a shared Proto-Germanic root related to the word 'full'. The sense has remained remarkably stable throughout its recorded history.
Related word forms
How fill is actually used
'Fill' is neutral in register and common in both speech and writing. Phrasal uses vary by dialect: 'fill in' a form is standard British usage, while American English often prefers 'fill out'; 'fill in' meaning 'to substitute for someone' is chiefly British, with Americans typically saying 'fill in for' or 'substitute'. The phrasal verb 'fill someone in' means to give them the latest information.
Easily confused with fill
'Fill' means to make full, while 'feel' means to perceive through touch or experience an emotion.