An auto-antonym is a word that can mean the opposite of itself. Some have seen an auto-antonym in Shakespeare,
The Winter's Tale 4.4.284:
Clamor your tongues, and not a word more.
See, e.g., the Folger Shakespeare Library edition of this play by Barbara A. Mowat and Paul Werstine (1998; rpt. New York: Simon & Schuster, 2009), p. 148:
Clamor: perhaps, silence (though the word usually means just the opposite)
The
Oxford English Dictionary, s.v. clamour | clamor,
v.1, neither recognizes this sense nor cites this line. According to Horace Howard Furness, ed.,
A New Variorum Edition of Shakespeare, Volume 11:
The Winter's Tale, 2nd ed. (Philadelphia: J.B. Lippincott Company, 1898), pp. 216-217, Croft conjectured
clam, Hanmer (and independently Gifford)
charm.