A one penis policy is an arrangement within a polyamorous relationship where the male partner is permitted to have intercourse with other females, but the females involved in the relationship are permitted only to have intercourse with other females not other men.
One Penis Policy
More About One Penis Policy
A one penis policy is the most common type of policy in polyamorous relationships when compared to the equivalent, which would be a one vagina policy. It is more common for the male partner in a polyamorous relationship of this style to have sexual freedom than for the female(s) to have the same freedom. Typically, in a relationship with a one penis policy the females are permitted to have intercourse with other females, but not with other males.