surfactant
B2CEFR level
55/100Rarity: uncommon
TechnicalRegister
A lipoprotein secreted by alveolar cells that lowers surface tension and prevents alveolar collapse.
Premature infants deficient in surfactant develop respiratory distress syndrome.
Rarity runs from 0 (a word everyone knows) to 100 (almost never seen outside specialist or literary writing). Level is the word's real difficulty on the CEFR scale, from A1 to C2.
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