|Definition - The linguist's favourite suffix to use when coining names for atomic units of lexical, grammatical, and phonological structure.|
Example - grapheme, lexeme, morpheme, phoneme, sememe, listeme, and toneme.
Oxford English Dictionary - The suffix's first citation is from 1953:
"A by-product of Linguistic Analysis … has been the sudden burgeoning of the -eme family."
(W. J. Entwistle Aspects of Lang. iii. 79 )