ri·val / ˈrīvəl/ • n. a person or thing competing with another for the same objective or for superiority in the same field of activity: he has no serious rival for the job | [as adj.] gun battles between rival gangs. ∎  a person or thing that equals another in quality: she has no rivals as a female rock singer.• v. (-valed, -val·ing; Brit. -valled, -val·ling) [tr.] compete for superiority with; be or seem to be equal or comparable to: the efficiency of the Bavarians rivals that of the Viennese.

rival sb. XVI. — L. rīvālis one who uses the same stream with another, f. rīvus stream; see -AL1.
Hence vb. XVII, rivalry XVI.

rival Pertaining to a stream or small river.