late 14c., "sudden violent muscular contraction," from Old French spasme (13c.) and directly from Latin spasmus "a spasm," from Greek spasmos "a spasm, convulsion," from span "draw up, tear away, contract violently, pull, pluck," from PIE *spe- "stretch." Figurative sense of "a sudden convulsion" (of emotion, politics, etc.) is attested from 1817.
word-forming element meaning "like, like that of, thing like a ______," from Latinized form of Greek -oeidēs (three syllables), from eidos "form," related to idein "to see," eidenai "to know;" literally "to see" (from PIE *weid-es-, from root *weid- "to see"). The -o- is connective or a stem vowel from the previous element. Often implying an incomplete or imperfect resemblance to the thing indicated.
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Definitions of spasmodic from WordNet
affected by involuntary jerky muscular contractions; resembling a spasm;