Definition of "colt"

The petty vices of boys are like the innocent kicks of colts, as yet imperfectly broken.

1857, Herman Melville, chapter XXII, in The Confidence-Man: His Masquerade

Ay, that's a colt indeed, for he doth nothing but / talk of his horse, and he makes it a great appropriation to / his own good parts that he can shoe him himself.

c. 1596–1598 (date written), William Shakespeare, “The Merchant of Venice”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene ii], line 38

Never talk on't: / She hath been colted by him.

1611 April (first recorded performance), William Shakespeare, “The Tragedie of Cymbeline”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene iv], line 133

What a plague mean ye to colt me thus?

c. 1597 (date written), William Shakespeare, “The First Part of Henry the Fourth, […]”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act II, scene ii], line 36

They shook off their bridles and began to colt.

1596 (date written; published 1633), Edmund Spenser, A Vewe of the Present State of Irelande […], Dublin: […] Societie of Stationers, […]; republished as A View of the State of Ireland […] (Ancient Irish Histories), Dublin: […] Society of Stationers, […] Hibernia Press, […] [b]y John Morrison, 1809,