Soy \Soy\, n. [Chinese sh[=o]y[=u].]

1. A Chinese and Japanese liquid sauce for fish, etc., made by subjecting boiled beans (esp. soja beans), or beans and meal, to long fermentation and then long digestion in salt and water.

2. (Bot.) The soja, a kind of bean. See Soja.

Source: Webster's Revised Unabridged Dictionary (1913)