- becoming obsolete; passing out of use, as a word: an obsolescent term.
- becoming outdated or outmoded, as machinery or weapons.
- Biology. gradually disappearing or imperfectly developed, as vestigial organs.
1755, from L. obsolescentum (nom. obsolescens), prp. of obsolescere "fall into disuse" (see obsolete). (http://dictionary.reference.com/browse/obsolescent)
"I often write in my diary the obsolete poem of self
with my obsolescent pen and ink."
- Stanley Moss, "The poem of self", 28 September 2015 The New Yorker (http://www.newyorker.com/magazine/2015/09/28/the-poem-of-self-poetry-stanley-moss)