One of the mysteries of the English language finally explained.
Definition of macrourid in US English:
macrourid
(also macrurid)
adjective
IchthyologyOf, relating to, or characteristic of the family Macrouridae of deep-water marine fishes with long tapering tails.
noun
IchthyologyA fish of the family Macrouridae; a rat-tail or grenadier.
Origin
1930s; earliest use found in John A. Thomson (1861–1933). From scientific Latin Macrouridae, family name from Macrourus, genus name (M. E. Bloch Ichtyologie v. 122; from macro- + ancient Greek οὐρά tail: see uro-) + -idae. Compare Hellenistic Greek μακρόουρος long-tailed (one isolated attestation), French macroure macrourid.