Thirteenth

Part of speech: adjective, noun

Pronunciation: /ˌθɜːˈtiːnθ/

Definitions

1. The ordinal indicator that signifies the position immediately after the twelfth in a sequence
2. A term indicating a rank or position that is directly after the twelfth in a sequential arrangement
3. An ordinal numeral that represents the position following the twelfth in any ordered series

Etymology: "Thirteenth" is a plain formation: the cardinal "thirteen" with the ordinal ending "-th" attached, the same suffix that turns "four" into "fourth" and "seven" into "seventh." The ending has a long pedigree in English, since Old English already used "-tēoþa" to build the ordinals of the teens, so "thirteenth" grew out of a native pattern rather than being borrowed from another language. The earliest form was Old English "þrēottēoþa," which passed into Middle English as "thrittenthe" and "thrittethe." Those medieval spellings show the word wearing down over time: the "-te-" of the cardinal and the ordinal ending blended together until the modern pronunciation, with its stress on the second syllable, took shape. The spelling "thirteenth" is simply the form that settled out of that process.