teenth

Teenth is a linguistic term used to describe the suffix -teenth, which appears in the English ordinal forms for thirteen through nineteen. The ordinals in this range are thirteenth, fourteenth, fifteenth, sixteenth, seventeenth, eighteenth, and nineteenth. The suffix -teenth marks a distinct small class of ordinals that differ from the more common -th ending used for most other numbers.

Etymology and formation: The cardinal numbers thirteen to nineteen are built from the stems three-, four-, five-, six-, seven-, eight-, nine- plus the suffix -teen. When forming ordinals, English generally adds the suffix -th to derive thirteenth, fourteenth, etc., but the result for 13–19 is typically described as using the teenth ending. Historically, the development reflects a combination of the teen-based numerals with the ordinal suffix, producing a unique set of forms that are phonologically and orthographically distinct from 1st–12th and 20th and beyond.

Usage: The teenth ordinals are used specifically for calendar dates, anniversaries, and other ordinal references that fall between the twelfth and twentieth positions. In practice, 13th through 19th are the standard forms, while 12th (twelfth) and 20th (twentieth) use irregular or different endings. The term teenth is mainly of interest in discussions of morphology and English historical development; it is not a separate word with independent meaning outside describing this suffixal category.

Examples: thirteenth, fourteenth, fifteenth, sixteenth, seventeenth, eighteenth, nineteenth, and, by contrast, twelfth and twentieth.

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