SIDE (3)

Side, v. i. [imp. & p. p. Sided; p. pr. & vb. n. Siding.] 1. 1. To lean on one side. Bacon.
2. 2. To embrace the opinions of one party, or engage in its interest, in opposition to another party; to take sides; as, to side with the ministerial party.
All side in parties, and begin the attack. Pope.