hypotonicity
|hy-po-to-nic-i-ty|
🇺🇸
/ˌhaɪpoʊtəˈnɪsəti/
🇬🇧
/ˌhaɪpəʊtəˈnɪsɪti/
state of low tension/pressure
Etymology
'hypotonicity' originates from modern English formation combining the prefix 'hypo-' (from Greek) and the adjective 'tonic' plus the nominalizing suffix '-ity'. Specifically, 'hypo-' comes from Greek 'ὑπό' ('hypo') meaning 'under' or 'below', 'tonic' derives from Greek 'τόνος' ('tonos') meaning 'tension' or 'stretch', and '-ity' is a Latin/Old French-derived suffix forming nouns.
'hypotonicity' developed from the adjective 'hypotonic' (formed from Greek elements in New Latin/19th-century scientific usage) with the addition of the noun-forming suffix '-ity', yielding 'hypotonicity' in modern English usage.
Initially the elements meant 'under' + 'tension/pressure' (a general sense of lower tension). Over time the compound came to be used specifically in physiology and medicine to mean 'low osmotic pressure' or 'reduced muscle tone'.
Meanings by Part of Speech
Noun 1
the state or quality of having lower osmotic pressure (tonicity) than another solution; a relatively low concentration of solutes causing water to move into the area of lower solute concentration.
The hypotonicity of the bathing solution caused the cells to swell as water entered.
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Noun 2
clinically, reduced muscle tone — an abnormally decreased resting tension in muscles (often referred to in medical contexts as hypotonia or hypotonicity).
On examination the infant displayed hypotonicity in the limbs, suggesting weak muscle tone.
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Last updated: 2025/12/10 05:01