allyl isothiocyanate
noun
allyl iso·thio·cy·a·nate
| \ -ˌī-sō-ˌthī-ə-ˈsī-ə-ˌnāt, -nət
\
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Medical Definition of allyl isothiocyanate
: a colorless pungent irritating liquid ester C4H5NS that is the chief constituent of mustard oil used in medicine and is used as a flavoring agent and as a medical counterirritant
— called also allyl mustard oil