Definition:Semiprime Number

Definition
A semiprime is an integer which is the product of two (not necessarily distinct) primes.

Examples
Obvious examples: if $p, p_1, p_2$ are prime, then:
 * $p^2$ is semiprime.
 * $2 p$ is semiprime.
 * $p_1 p_2$ is semiprime.

Also known as
Some sources refer to a semiprime as an almost-prime.