Penta-
Penta- , prefix
[Greek penta-, a later combining form of pe`nte five. See Five.]
1.
A combining form denoting five; as, pentacapsular; pentagon.
2.
(Chemistry) Denoting the degree of five, either as regards quality, property, or composition; as, pentasulphide, containing five sulfur atoms; pentoxide, containing five oxygen atoms, etc. Also used adjectively.