1 n.
a Canadian one-dollar coin (see Image 1).
Type: 1. Origin — The coin was introduced in 1987 and almost immediately acquired this nickname (see the three 1987 quotations) because it has a loon on one side (see Image 1). The loon design was chosen after the dies with the first design were lost (see the first and third 1987 quotations) and the actual release of the coin did not go as planned (see the third 1987 quotation). The "looniness" surrounding its origins may have encouraged the term's entrenchment.
See also COD-2, s.v. "loonie" (1), which labels this meaning "Cdn", OED-3, s.v. "loonie", labeled as "Canad. colloq."
See also: toonie loonie store
- The 1989 quotation offers interesting information on spelling variants, which, by that time seem to have already been decided in favour of loonie.
2 n. — Finance, informal
the Canadian dollar.
Type: 1. Origin — See COD-2, s.v. "loonie" (2), which labels the meaning ""Cdn".
3 n. — usually plural, informal
money in general.
Type: 1. Origin — An extension of meanings 1 and 2.
Images:

Image 1: A loonie. Photo: S. Gaylie