#1 fill in v. supply with information on a specific topic; "He filled me in on the latest developments". wn
#2 fill in v. represent the effect of shade or shadow on. wn
#3 fill in v. be a substitute; "The young teacher had to substitute for the sick colleague"; "The skim milk substitutes for cream--we are on a strict diet". wn
#4 fill in v. write all the required information onto a form; "fill out this questionnaire, please!"; "make out a form". wn
vizzz