prep by of before the time that; in preparation for; so as to be ready for the time when.
2. against ·prep abreast; opposite to; facing; towards; as, against the mouth of a river;
in this sense often preceded by over.
3. against ·prep from an opposite direction so as to strike or come in contact with; in contact with; upon; as, hail beats against the roof.
4. against ·prep in opposition to, whether the opposition is of sentiment or of action; on the other side; counter to; in contrariety to; hence, adverse to; as, against reason; against law; to run a race against time.