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 ]