Pentomic

Pentomic (cf.Greek pent(e)- and -tome, "of five parts") refers to a structure for infantry and Airborne divisions adopted by the U.S. Army in 1957 in response to the perceived threat posed by tactical nuclear weapons use on the battlefield.

"Pentomic Division" was "a public relations term designed to combine the concept of five subordinate units ('penta') with the idea of a division that could function on an atomic or nonatomic battlefield."