Unsaturated \Un*sat"u*ra`ted\, a.

1. Capable of absorbing or dissolving to a greater degree; as, an unsaturated solution.

2. (Chem.) Capable of taking up, or of uniting with, certain other elements or compounds, without the elimination of any side product; thus, aldehyde, ethylene, and ammonia are unsaturated.

Source: Webster's Revised Unabridged Dictionary (1913)