Definition of: against

(ə·genst′. esp. Brit, ə·gānst′) prep.
1. In contact with and pressing upon: leaning against the wall.
2. In collision with: The ship was dashed against the rocks.
3. In front of; directly opposite: against the background of the sky.
4. In anticipation of; in preparation for: to be ready against the third day; to hoard wealth against old age.
5. In opposition to; contrary to: against my wishes.
6. In hostility to: fighting against the invader.
7. To the debit of: Charge it against my account.
8. In comparison with; contrasted with: my word against yours. [OE ongegn + -es, adverbial genitive suffix + inorganic -t]