"Bihamut" is a portmanteau of the words "bi" and "Bahamut".
"Bi-" is the numeral prefix commonfly associated with the number "two", which reflects this monster's two heads.
"Bi" also shares a similar pronunciation with "bai", the Chinese word for the color "white", reflecting this monster's color scheme and associated "White" archetype.
"Bahamut" is a giant primordial fish in Arabian mythology who helps support the Earth and is suspended in water for its own stability.
In the English version of the Yu-Gi-Oh! ARC-V manga, this card's name is "Biphamet", which is a portmanteau of the words "bi" and "Baphomet".
The heads of this monster are based on Dunkleosteus, an extinct species of large predatory fish, reflecting the depiction of the Bahamut as a giant primordial fish.