Branchial \Bran"chi*al\, a. (Anat.) Of or pertaining to branchi[ae] or gills.

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.

Source: Webster's Revised Unabridged Dictionary (1913)