1) Avian tub 2) Avian water source 3) Backyard attraction 4) Backyard basin for sparrows 5) Basin 6) Functional lawn adornment 7) Piece of garden statuary 8) Pool on a pedestal 9) Small pool site in a yard 10) Where finches splash 1) Cardinalbasin 
Birdbath is British slang for a silly person.
[n] - an ornamental basin (usually in a garden) for birds to bathe in
noun an ornamental basin (usually in a garden) for birds to bathe in
a basin or tublike garden ornament for birds to drink from or bathe in.