silver dollar

Short definition from Wiktionary

Noun

1. 1
   A dollar coin, whether made from silver or not.
2. 2
   A small pancake.
3. 3
   Several species of tropical freshwater fish of the genus Metynnis, of the family Characidae or Serrasalmidae, of which Metynnis argenteus is one; popular for aquariums; so named from their shape and flashing silver color.