prime implicant

Meanings

1. A group of related 1's (implicant) on a Karnaugh map which is not subsumed by any other implicant in the same map. Equivalently (in terms of Boolean algebra), a product term which is a "minimal" implicant in the sense that removing any of its literals will yield a product term which is not an implicant (but beware: on a Karnaugh map it would appear "maximal").
2. A group of related 0's (implicant) on a Karnaugh map which is not subsumed by any other implicant (of 0's) in the same map.

Etymology

An implicant (Boolean product term) which is called "prime" because none of its proper factors is itself an implicant.