Teens
来自Big Physics
late 16th century: as plural noun, as an independent usage of -teen. Sense 2 of the noun dates from the early 19th century, and the adjective from the 1920s.
wiktionary
The final syllable of the numbers from thirteen to nineteen. More at teen.
etymonline
teens (n.)
1670s (plural), "teen-age years of a person," formed from -teen taken as a separate word. As "decade of years comprising numbers ending in -teen," from 1889.
