The Collaborative International Dictionary
Pentamerous
Pentamerous \Pen*tam"er*ous\, a. [Penta- + Gr. ? part.]
(Biol.) Divided into, or consisting of, five parts; also, arranged in sets, with five parts in each set, as a flower with five sepals, five petals, five, or twice five, stamens, and five pistils.
(Zo["o]l.) Belonging to the Pentamera.
Wiktionary
pentamerous
a. (context botany English) In five parts; made up of five parts.
WordNet
pentamerous
adj. divided into five parts; specifically, having each floral whorl consist of five (or a multiple of five) members; "pentamerous flowers"