Plural of entasia; multiple instances or types of sustained involuntary muscle contraction or tension.
From 'entasia' with the Latin/Greek plural ending '-as' becoming '-s' in English. Medical terminology following Latinate pluralization conventions.
Scientific terminology often preserves Latin and Greek plural forms in English (stimulus/stimuli, datum/data), though 'entasias' shows how English speakers often simplify by just adding '-s' to everything.
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