hummingbird UK /ˈhʌmɪŋˌbɜːd/US /ˈhʌmɪŋˌbɜɹd/ noun1 •Any of various small American birds in the family Trochilidae that have the ability to hover.Soon I hear the low all-pervading hum of an approaching hummingbird circling above the rock, … — 1857 formshummingbirds