Of a part of the body: that performs a special function; that is an organ. Also: of or relating to an organ. Cf. instrument, n. 4. Now historical and…

Biology and Medicine. = organic, adj. 2a. Esp. in organical part. Obsolete.

Of a part of the body: that performs a special function; that is an organ. Also: of or relating to an organ. Obsolete.

Of a part of the body: that performs a special function; = instrumental, adj. 2. Cf. instrumentary, adj. 1.

Serving, or designed to serve, a function; having a practical purpose; (hence) practical, useful.