verb
To insert
write in, answer, complete; see complete 1, fill out 2.
To substitute
replace, act for, represent; see substitute 2.
To inform
apprise, acquaint, bring up to date, clue in*; see notify 1.
See fill in in Webster's New World Roget's A-Z Thesaurus II
One that takes the place of another:
Learn more about fill in
fill-in definition
fill in phrase meanings
fill in in a sentence
Also Mentioned In
alternate
base
breaker
chaser
complete
develop
fill
filler
flash
linkup
» more results...
Browse entries near fill in
filibuster
filiform
filigree
fill a prescription
fill an order
fill out
fill up
filled
fillet