Source : Webster's Revised Unabridged Dictionary (1913)

Groat \Groat\, n. [LG. gr[=o]te, orig., great, that is, a great
   piece of coin, larger than other coins in former use. See
   {Great}.]
   1. An old English silver coin, equal to four pence.

   2. Any small sum of money.

Source : WordNet®

groat
     n : a former English silver coin worth four pennies [syn: {fourpence}]