Lacking normal muscle tone or tension; weak and floppy; in linguistics, referring to a syllable or word without stress.
From Greek a- (without) + tonos (tone). Used in both medical contexts (muscle tone) and linguistic contexts (stress in speech) since the 1800s.
In English, atonic syllables are the ones you don't stress—like the 'a' in 'about'—and they're actually harder for foreign speakers to hear because we rush through them!
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