Other forms: filled, filling, fills
To fill something is to put so much in that no empty space is left. Fill the kettle, fill a form, the room filled with smoke.
It works both ways: you fill something, and something fills. The phrasal verbs do a great deal of work and split by country: fill in a form is British, fill out a form is American, and both are understood everywhere. Fill up is for tanks and for people. Fill in for somebody means to take their place temporarily, and fill somebody in means to tell them what they missed. The noun is a fill, mostly in have your fill, meaning as much as you want.
1verbfillTo put enough into something that no space is left.
“Fill the jug and put it on the table.”
2verbbecomeTo become full.
“The hall filled quickly once the doors opened.”
3verbcompleteTo complete a form by writing in it.
“Fill in your details and sign at the bottom.”
4verboccupyTo occupy a position or a period of time.
“The post has been filled.”
Too few real examples of this word to estimate which sense is commonest.
fill is a way of making full.
Old English fyllan comes from full — filling is simply making full, and the two have never drifted apart. The same root gives fulfil, which is full plus fill, saying the same thing twice for emphasis.
Proto-Indo-European
*pleh₁-
Middle English
fillen
English, today
fill
Built from
From Middle English fillen. From Middle English fillen, fullen, from Old English fyllan (“to fill, fill up, replenish, satisfy; complete, fulfill”), from Proto-West Germanic fullijan, from Proto-Germanic fullijaną (“to make full, fill”), from fullaz (“full”), from Proto-Indo-European pl̥h₁nós (“full”). Cognate with Scots fill (“to fill”), West Frisian folje (“to fill”), Low German füllen (“to fill”), Dutch vullen (“to fill”), German füllen (“to fill”), Danish fylde (“to fill”), Swedish fylla (“to fill”), Norwegian fylle (“to fill”), Icelandic fylla (“to fill”) and Latin plenus (“full”)
Etymology from Wiktionary, CC BY-SA