Definitions of -ous

1. A suffix denoting that the element indicated by the name bearing it, has a valence lower than that denoted by the termination - ic; as, nitrous, sulphurous, etc., as contrasted with nitric, sulphuric, etc.

2. A suffix denoting that the element indicated by the name bearing it, has a valence lower than that denoted by the termination - ic; as, nitrous, mercurous, ferrous, sulphurous, etc., as contrasted with nitric, mercuric, ferric, sulphuric, etc.