Liddell-Scott-Jones

ματαίως (mataiōs) acting in folly ^G:ADV

Included with: ματαίως-ος [μᾰ], α, ον

[Refs 4th c.BC+]; also ος, ον[Refs 5th c.BC+]: (μάτη):—

__I vain, empty, idle:
__I.1 of words, acts, etc., ματαίωςα νομίζομεν [Refs 6th c.BC+]; μ. λόγοι idle tales or words, [Refs 5th c.BC+].; μ. ἔπεα[Refs 4th c.BC+]; μ. ὑλάγματα, ποιφύγματα,[Refs]; μ. εὐχή E.[same place]; ματαίωςα βάζειν τινά [Refs 5th c.BC+]; μ. ἡδονή S.[same place]; δοξοσοφία [Refs 5th c.BC+]; τὰ μ. ἀναλώματα useless expenses, [Refs 3rd c.AD+]; but also, μ. ἔπος a word of offence, [Refs 5th c.BC+]
__I.2 of persons, empty, foolish, ματαιότεροι νόον [Refs 6th c.BC+]; φῦλον ματαιότατον [Refs 5th c.BC+]; worthless, [Refs 5th c.BC+]
__II rash, irreverent, profane, frequently in [Refs 4th c.BC+]; αὐτουργίαι μ., of matricide and the like, “Eu.” [same place]; χαρὰ μ. mad merriment, [Refs]; τὸ μὴ μ. seriousness, gravity,[Refs 5th c.BC+]
__III adverb -ως idly, without ground,[Refs 5th c.BC+]; μ. ἐρεῖν to no purpose, [Refs 5th c.BC+]