In Old English the common name for any of the flatfish, skate, turbot, plaice, flounder, or whatever, was “butt.”
The most highly regarded of all, however, the one that was reserved for eating upon holy days, was the largest of the flatfishes, so large that fish weighing three and four hundred pounds are not uncommon, running up to seven or eight feet in length.
This they named the haly butt, for haly was the old-time spelling of holy.
The consumption of the halibut is no longer limited to feast days of the Church, despite our designation of the fish as “the holy flounder.”
