Dutch word koppig comes from Dutch -ig, Dutch kop

Detailed word origin of koppig

Dictionary entry	Language	Definition
-ig	Dutch (nld)	-ed, having (when attached to a noun preceded by an adjective that describes the noun). -y; forms adjectives from nouns.
kop	Dutch (nld)	(colloquial, by extension) A (male) human.. (derogatory, for humans) head. Cup (for drinking). Front, lead, e.g. in a race; charge, control.. Head of a nail, pin etc.. Heading (of a text), headline. Heads (side of a coin).
koppig	Dutch (nld)	Stubborn, obstinate.

Words with the same origin as koppig