Definify.com
Webster 1913 Edition
Sinapism
Sin′a-pism
,Noun.
[L.
sinapismus
, Gr. [GREEK][GREEK][GREEK][GREEK], the use of a mustard blister, fr. [GREEK][GREEK][GREEK] to apply a mustard blister, fr. [GREEK][GREEK][GREEK][GREEK] mustard.] (Med.)
A plaster or poultice composed principally of powdered mustard seed, or containing the volatile oil of mustard seed. It is a powerful irritant.