English Etymology From an- + acanthous. Adjective anacanthous (not comparable) Spineless, like certain fishes, such as certain extinct sharks Related terms anacanthobatid References “anacanthous”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.Wikiwand - on Seamless Wikipedia browsing. On steroids.