halibut

UK: /ˈhælɪbət/ US: /ˈhæləbət, ˈhɑl-/ ,(hal′ə bət, hol′-)

Inflections of 'halibut' (n):

halibut

npl (Especially as a collective plural—e.g. "That fisherman has a good catch of halibut.")

halibuts

npl (Mainly used to talk about different types—e.g. "Halibuts include the Atlantic halibut and the Pacific halibut.")

WordReference Random House Learner's Dictionary of American English © 2025

hal•i•but /ˈhæləbət, ˈhɑl-/   n., pl. (esp. when thought of as a group) -but, (esp. for kinds or species) -buts. 

1. Fish any of various large flounders used for food.

WordReference Random House Unabridged Dictionary of American English © 2025

hal•i•but  (hal′ə bət, hol′-), n., pl. (esp. collectively) -but,  (esp. referring to two or more kinds or species) -buts. 

1. Fish either of two large flatfishes, Hippoglossus hippoglossus, of the North Atlantic, or H. stenolepis, of the North Pacific, used for food.
2. Fish any of various other similar flatfishes.

Also, holibut. 

• Middle Dutch); so called because eaten on holy days. Compare Dutch heilbot, German Heilbutt
• Middle English halybutte, equivalent. to haly (variant of holy) + butte flat fish (1350–1400

Collins Concise English Dictionary © HarperCollins Publishers::

halibut / ˈhælɪbət/, holibut / ˈhɒlɪbət/ noun ( -buts, -but)

1. the largest flatfish: a dark green North Atlantic species, Hippoglossus hippoglossus, that is a very important food fish: family Pleuronectidae

Etymology: 15th Century: from hali holy (because it was eaten on holy days) + butte flat fish, from Middle Dutch butte