Side \Side\, v. i. [imp. & p. p. Sided; p. pr.& vb. n. Siding.]

1. To lean on one side. [Obs.]

--Bacon.

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.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Siding \Sid"ing\, n.

1. Attaching one's self to a party.

2. A side track, as a railroad; a turnout.

3. (Carp.) The covering of the outside wall of a frame house, whether made of weatherboards, vertical boarding with cleats, shingles, or the like.

4. (Shipbuilding) The thickness of a rib or timber, measured, at right angles with its side, across the curved edge; as, a timber having a siding of ten inches.

Source: Webster's Revised Unabridged Dictionary (1913)