colt's tooth

From Middle English coltes tooth.

colt's tooth (plural colt's teeth)

1. One of a horse's first set of teeth.
2. (figuratively) Youthful desires, especially lust.
   • 1613 (date written), William Shakespeare, [John Fletcher], “The Famous History of the Life of King Henry the Eight”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act I, scene iii], page 210, column 1:

     Well ſaid Lord Sands,
     Your Colts tooth is not caſt yet?

   • 1723, Charles Walker, Memoirs of Sally Salisbury, section V:

     his Worship, who had still a Colt's-Tooth in his Head, cast an amorous Leer upon SALLY [...] Let me view her again, says the Justice, calling for his Spectacles, and at the same time gave her a gentle Squeeze by the Hand [...].