thunderbird n 1: (mythology) the spirit of thunder and lightning believed by some Native Americans to take the shape of a great bird
Thunderbird \Thun"der*bird`\, n. (Zool.) An Australian insectivorous singing bird ({Pachycephala gutturalis}). The male is conspicuously marked with black and yellow, and has a black crescent on the breast. Called also {white-throated thickhead}, {orange-breasted thrust}, {black-crowned thrush}, {guttural thrush}, and {black-breasted flycatcher}. [1913 Webster]
Thunderbird <messaging, open source> A complete {free}, {open-source} {e-mail client} from the {Mozilla Foundation} and therefore a true code descendent of the e-mail code in {Netscape Navigator}. The first non-{beta release} was in late 2004. The {Firefox} web browser is from the same source. Thunderbird Home (http://mozilla.org/products/thunderbird). (2005-01-26)