Word Study
butyl
CIDE DICTIONARY
butyl, n. [L. butyrum butter + -yl. See Butter.].
A compound radical, regarded as butane, less one atom of hydrogen. [1913 Webster]
OXFORD DICTIONARY
butyl, n. Chem. the univalent alkyl radical C4H9.
Idiom
butyl rubber a synthetic rubber used in the manufacture of tyre inner tubes.
Etymology
BUTYRIC (ACID) + -YL
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