‖n.; pl. Branchiæ [ L., fr. Gr. &unr_;, pl. of &unr_;. ] (Anat.) A gill; a respiratory organ for breathing the air contained in water, such as many aquatic and semiaquatic animals have. [ 1913 Webster ]

a. (Anat.) Of or pertaining to branchiæ or gills. [ 1913 Webster ]

Branchial arches, the bony or cartilaginous arches which support the gills on each side of the throat of fishes and amphibians. See Illustration in Appendix. --
Branchial clefts, the openings between the branchial arches through which water passes. [ 1913 Webster ]

a. (Anat.) Furnished with branchiæ; as, branchiate segments. [ 1913 Webster ]