combining form
Etymology: Latin, one and a half, half again, literally, and a half, from semis half (from semi- ) + -que and (enclitic); akin to Greek te and, Sanskrit ca, Gothic -h, -uh — more at semi-
1. : one and a half times
sesqui centennial
2. archaic : more than the norm of the type : super- , ultra-
sesqui heretic
3. : one and a half times the degree of a (specified) aspect in astrology
sesqui quadrate
4.
a. : containing three atoms or equivalents of a (specified) element or radical especially when combined with two of another
sesqui oxide
sesqui sulfide
b. : intermediate : combination — not used systematically
sesqui carbonate
sesqui silicate
c. : containing half again as many atoms
sesqui terpene