The Collaborative International Dictionary
Pentacron
Pentacron \Pen*ta"cron\, n.; pl. L. Pentacra, E. Pentacrons. [NL., fr. Gr. ? five + ? a summit.] (Geom.) A solid having five summits or angular points.
Wiktionary
pentacron
n. (context geometry English) A solid with five summits or angular points.