TROCHILUS, in ornithology, a genus belonging to the order of picæ. The beak is subulated and thread-shaped, with a tubular apex, and longer than the head, the superior mandible sheathing the inferior; the tongue is thread-shaped; and the feet are fitted for walking. This genus comprehends all the humming birds, which are the smallest of birds, and are distinguished by their colour and the shape of their bills.