germane adj.

"of the same parents or grandparents," c. 1300, from Old French germain "own, full; born of the same mother and father; closely related" (12c.), from Latin germanus "full, own (of brothers and sisters); one's own brother; genuine, real, actual, true," related to germen (genitive germinis) "sprout, bud," which is of uncertain origin; perhaps it is a dissimilation of PIE *gen(e)-men-, suffixed form of root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups.

Your cousin-german (also first cousin) is the son or daughter of an uncle or aunt; your children and your first cousins are second cousins to one another; to you, your first cousin's children are first cousins once removed.

1530s, "of or relating to cities or towns," from French urbain (14c.) and directly from Latin urbanus "belonging to a city," also "citified, elegant" (see urban). The meaning "having the manners of townspeople, courteous, refined" is from 1620s, from a secondary sense in classical Latin. Urbanity in this sense is recorded from 1530s. For sense connection and differentiation of form, compare human/humane; german/germane.

Urbane; literally city-like, expresses a sort of politeness which is not only sincere and kind, but peculiarly suave and agreeable. [Century Dictionary]