before vowels pycn-, word-forming element meaning "close, thick, dense," from Latinized combining form of Greek pyknos "thick, dense, solid, compact; numerous; strong; brave; clever," which is of uncertain origin. Often in English via German as pykno-.
Entries linking to pycno-
pycnometer n.
"instrument for determining the relative density of solid bodies," by 1858; see pycno- + -meter.