any of a large family (Trochilidae, order Apodiformes) of very small, brightly colored, New World birds with a long, slender bill for feeding on nectar, and narrow wings that vibrate rapidly, often with a humming sound
See hummingbird in American Heritage Dictionary 4
noun
Any of numerous New World birds of the family Trochilidae, usually very small in size and having brilliant iridescent plumage, a long slender bill, and wings capable of beating very rapidly, thereby enabling the bird to hover.