early 15c. (implied in congested), of body fluids, "to accumulate," from Latin congestus, past participle of congerere "to bring together, pile up," from assimilated form of com "with, together" (see con-) + gerere "to carry, perform" (see gest). Sense of "overcrowd" is from 1859. Related: Congested; congesting.

"a thing of the same kind as, or nearly allied to, another," 1730s, from French congénère (16c.), from Latin congener "of the same race or kind," from assimilated form of com "with, together" (see con-) + gener-, stem of genus "race, kind" (from PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups). Related: Congenerous (1640s); congeneracy.