Late 19th century; earliest use found in Johnson's New Universal Cyclopedia. From scientific Latin Petromyzontidae, family name from Petromyzont- + -idae.
Definition of petromyzontid in US English:
petromyzontid
nounˌpɛtrə(ʊ)mʌɪˈzɒntɪd
Zoology
A fish of the family Petromyzontidae; a lamprey.
Origin
Late 19th century; earliest use found in Johnson's New Universal Cyclopedia. From scientific Latin Petromyzontidae, family name from Petromyzont- + -idae.