The Collaborative International Dictionary
Lupulin
Lupulin \Lu"pu*lin\, n. [Cf. F. lupulin. See Lupuline.]
(Chem.) A bitter principle extracted from hops.
The fine yellow resinous powder found upon the strobiles or fruit of hops, and containing this bitter principle.
Wiktionary
lupulin
n. (context botany English) Small hairs gotten from the strobili of the hop plant.