Definition - A consonant formed by using the tongue to partially close the mouth's air-passage so that the breath escapes on one or both sides of the contact point.

Example -
The English /l/ sound as in love is a lateral.

Etymology -
The word derives from the Latin lateralis, belonging to the side (from latus, side).

Oxford English Dictionary -
Its first citation is from 1891:
"Some persons … let the breath escape on one side only, so it seems better to call it [l] a lateral or side consonant."
(L. Soames Introd. Phonetics 34)

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