Meaning

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

adjective being one more than seventeen

originEtymology tree Proto-Indo-European *oḱtṓw Proto-Germanic *ahtōu Proto-Indo-European *déḱm̥ Proto-Germanic *tehun Proto-Germanic *ahtōutehun Anglian Old English eahtatēne Middle English eightetene English eighteen From Middle English eightetene, eiȝtene, ehtetene, from Old English eahtatīene, eahtatēne, from Proto-Germanic *ahtōutehun. Cognate with West Frisian achttjin, Dutch achttien, German…

Etymology from Wiktionary, CC BY-SA 3.0