A lock of hair over the ear.

1

a. 1775.  “General Health, who was a member of the committee, rode to take command of the provincials, with Warren by his side, who was sufficiently exposed that day to have a musket ball strike the pin out of the hair of his ear-lock.”—T. W. Higginson, ‘The Dawning of Independence,’ Harper’s Mag. (Oct., 1883), lxvii. p. 736/1. (N.E.D.)

2

1793.  An essenced beau, with ear locks well larded and mealed.—Mass. Spy, Sept. 26.

3

1809.  His hair strutting out on each side in stiffly pomatumed ear-locks, and descending in a rat-tail queue below the waist.—W. Irving, ‘Knickerbocker’s History of New York’ (1861), p. 183. (N.E.D.)

4

1843.  

        Yet his whiskers so fine were curled with much taste,
And his smoothly-combed ear-locks fell down to his waist.
‘Lowell Offering,’ iv. 12, ‘A Scene in Elysium.’    

5

1855.  The little that was left of his hair above his forehead was brushed stiffly upwards, and his long earlocks, which, whilome were wont to hang straight adown his cheeks, were curled and frizzled into knots like rosettes above each red and shapeless ear.—C. W. Philleo, ‘Twice Married,’ Putnam’s Mag., vi. 239/2 (Sept.).

6

1867.  

        His ear-locks gray, striped with a foxy brown,
Were braided up to a hide a desert crown.
James R. Lowell, ‘Fitz-Adam’s Story.’    

7