Ladies and gents!
Welcome to 2019 and the very first Fun Etymology of the year!
Speaking of the new year, this year is the last -teen-year of the century (nineTEEN, that is)! In honour of that, today’s word is more of a word-forming element: you guessed it, it’s -teen!
This word-forming element marks cardinal numbers from 13 to 19 and means “ten more than”, so “ten more than 9” = 19.
It comes to us from Anglian Old English -tēne, West Saxon -tiene, which developed from an inflected form of Proto-Germanic *tehun, meaning “ten”. The Proto-Germanic word comes from Proto-Indo-European *déḱm̥t. In this element, we can see a real sound change happening: the English element -teen is cognate with Italian -dici, from Latin -decim. Notice that the PIE word which they come from starts with a <d> and so does the derived word in Latin and Italian? But in English, it starts with a <t>! Isn’t that just a beautiful example of Grimm’s Law?
Welcome to the year two thousand and nineteen, friends, and to another year of language fun!