Etymology
Borrowed from French terne, from Middle French, from Old French terne (“dim, dull”), from Frankish *darnī (“concealed, hidden; secret”); further etymology unknown, perhaps related to Proto-West Germanic *derk (“dark; dirty”), perhaps ultimately from Proto-Indo-European *dʰerg- (“to darken, dim”). Doublet of dern.
Definitions & examples from Wiktionary (CC BY-SA 3.0).