Definition -
(1) A phoneme produced by a blockage or constriction of the vocal track.
(2) An alphabetical character that represents one of these phonemes.

Example -
The sound /b/ and the letter b are both consonants.

Etymology -
The word derives from the Latin consonare, to sound together (from com, with + sonare, to sound).

Oxford English Dictionary -
Its first citation is from circa 1308:
"Þis uers is imakid wel Of consonans and wowel."
(Sat. People Kildare 18 in E.E.P. (1862) 153)

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