The Collaborative International Dictionary of English v.0.48:

Twopence \Two"pence\ (?; 277), n.
   A small coin, and money of account, in England, equivalent to
   two pennies, -- minted to a fixed annual amount, for
   almsgiving by the sovereign on Maundy Thursday.
   [1913 Webster]

WordNet (r) 3.0 (2006):

twopence
    n 1: a former United Kingdom silver coin; United Kingdom bronze
         decimal coin worth two pennies [syn: twopence,
         tuppence]