D defs.my
Entry 4 senses Webster, 1913

Against

/əg-ĕnst'/ · A·gainst · IPA /əˈɡɛnst/
01 prep. Abreast; opposite to; facing; towards; as, against the mouth of a river; -- in this sense often preceded by over.
  1. 1.
    Abreast; opposite to; facing; towards; as, against the mouth of a river; -- in this sense often preceded by over.
    “Jacob saw the angels of God come against him.” — Tyndale.
  2. 2.
    From an opposite direction so as to strike or come in contact with; in contact with; upon; as, hail beats against the roof.
  3. 3.
    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.
    “The gate would have been shut against her.” Fielding.
    “An argument against the use of steam.” — Tyndale.
  4. 4.
    By of before the time that; in preparation for; so as to be ready for the time when.[Archaic or Dial.]
    “Urijah the priest made it, against King Ahaz came from Damascus.” — 2 Kings xvi. 11.
Phrases & compounds
Against the sun — in a direction contrary to that in which the sun appears to move.