Meaning of against

a•gainst

1. in opposition to; contrary to; adverse or hostile to: twenty votes against ten; against reason.
2. in resistance to or defense from: protection against burglars.
3. in an opposite direction to: to ride against the wind.
4. into contact or collision with; toward; upon: The rain beat against the window.
5. in contact with: to lean against the wall.
6. in preparation for; in provision for: money saved against a rainy day.
7. having as background: a design of flowers against a dark wall.
8. in exchange for; as a balance to or debit or charge on: He asked for an advance against his salary.
9. in competition with: a racehorse running against his own record time.
10. in comparison or contrast with: a matter of reason as against emotion.
11. beside; near; before: The car is against the building.
12. in contrast with: the rich over against the poor.

1. before; by the time that.