Meaning

noun the cardinal number that is the sum of twelve and one

adjective being one more than twelve

originFrom Middle English thirttene, variant (through metathesis) of thrittene, from Old English þrēotīene, from Proto-Germanic *þritehun, compound of *þrīz (“three”) + *tehun (“teen”). Cognate with West Frisian trettjin, Dutch dertien, German dreizehn, Danish tretten. Equivalent to three + -teen.

Etymology from Wiktionary, CC BY-SA 3.0