dime pronunciation: function: noun etymology: middle english, tenth part, tithe, from anglo-french disme, dime, from latin decima, from feminine of decimus tenth, from decem ten — more at tendate: 1786 1 a : a coin of the united states worth 1?10 dollar b : a petty sum of money2 : a canadian 10-cent piece3 slang : a packet containing 10 dollars worth of an illicit drug (as marijuana) —called also dime bag— a dime a dozen : so plentiful or commonplace as to be of little esteem or slight value— on a dime 1 : in a very small area lt;these cars can turn on a dimegt;2 : instantly