1 in opposition to (fight against the invaders; am against hanging; arson is against the law).
2 into collision or in contact with (ran against a rock; lean against the wall; up against a problem).
3 to the disadvantage of (his age is against him).
4 in contrast to (against a dark background; 99 as against 102 yesterday).
5 in anticipation of or preparation for (against his coming; against a rainy day; protected against the cold; warned against pickpockets).
6 as a compensating factor to (income against expenditure).
7 in return for (issued against payment of the fee).
Phrases and idioms:
against the clock see CLOCK(1) 3. against the grain see GRAIN. against time see TIME.
Etymology: ME ayenes etc. f. ayen AGAIN + -t as in amongst: see AMONG
Useful english dictionary. 2012.