AGAINST, prep. agenst'.
1. In opposition noting enmity or disapprobation.
His hand will be against every man. Genesis 16 .
I am against your pillows. Ezekiel 8 .
2. In opposition, noting contrariety, contradiction, or repugnance as, a decree against law, reason or public opinion.
3. In opposition, noting competition, or different sides or parties as, there are twenty votes in the affirmative against ten in the negative.
4. In an opposite direction as, to ride against the wind.
5. Opposite in place abreast as, a ship is against the mouth of a river. In this sense it is often preceded by over.
Aaron lighted the lamps over against the candlesticks.
Numbers 8 .
6. In opposition, noting adversity, injury, or contrariety to wishes as, this change of measures is against us.
7. Bearing upon as, one leans against a wall.
8. In provision for in preparation for.
Urijah made it against king Ahaz came from Damascus.
2 Kings 16.
In this sense against is a preposition, with the following part of the sentence for an object. See After, prep. def. 2.
In short, the sense of this word is opposition, variously modified according to its application to different objects.