obsolete

Definitions:

Gone out of use; disused; out of date; in bot., imperfectly developed or abortive- applied to the calyx when it is in the form of a rim; in zool., applied to a part or spot, or to some distinctive character scarcely discoverable.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (adjective) (adj.) (adjective)
Wearing out or disappearing ; any character that is becoming less and less distinct in each succeeding generation.
- A dictionary of scientific terms. By Henderson, I. F.; Henderson, W. D. Published 1920. (adjective) (adj.) (adjective)
Gone into disuse; not fully developed; indistinct.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (adjective) (adj.) (adjective)
Gone out of use: antiquated: ( zool.) obscure: rudimental.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (adjective) (adj.) (adjective)
Gone out of use; antiquated.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (adjective) (adj.) (adjective)
Gone out of use; as, obsolete firearms; no longer practiced or accepted; as, an obsolete custom; old.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (adjective) (adj.) (adjective)
Obsoleteness.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (noun) (n.) (noun)

Usage examples:

It was an obsolete
- Thy Rocks and Rills by Robert Ernest Gilbert
This function of the state has now become almost obsolete
- Equality by Edward Bellamy
True it is that if we want ivory animals must be killed to get it, for the notion that some people have gained from obsolete works on natural history, to the effect that elephants shed their tusks, is an erroneous one.
- Natural History of the Mammalia of India and Ceylon by Robert A. Sterndale