The Collaborative International Dictionary of English v.0.48:
Sixpence \Six"pence\, n.; pl. Sixpences. An English silver coin of the value of six pennies; half a shilling, or about twelve cents. [1913 Webster]WordNet (r) 3.0 (2006):
sixpence n 1: a small coin of the United Kingdom worth six pennies; not minted since 1970 [syn: sixpence, tanner]