The term Lacaean is without parallel in Greek but would presumably be related to Lacaenian, i.e. Spartan (beta 166, lambda 47, etc.). Lacaean (λάκαιον ) is neuter, nominative/accusative singular. λακαίνης is feminine, genitive singular; and this latter is probably lifted bodily from its occurrence in lambda 47 immediately preceding.
The source of the headword phrase is unknown.