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

Source: The Collaborative International Dictionary of English v.0.48
 

branchial adj : of or relating to gills (or to parts of the body derived from embryonic gills)

Source: WordNet (r) 2.0
 

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)