[əˈɡeɪnst], (Adposition)

Definitions:
- in opposition to
(e.g: the fight against crime)

- in anticipation of and preparation for (a problem or difficulty)
(e.g: he gritted his teeth against the pain)

- in or into physical contact with (something), so as to be supported by or collide with it
(e.g: she stood with her back against the door)

- in conceptual contrast to
(e.g: the benefits must be weighed against the costs)


Phrases:
- against one's wishes
- against the law
- against the rules
- have something against someone

Origin:
Old English agenes, from again + -s (adverbial genitive) + -t, probably because the word was frequently followed by te, variant of the, and perhaps also by association with superlatives in -st (such as amongst)