Quick Definition
εἰκῇ Adv without purpose, in vain
Strong's Definition
probably from 1502 (through the idea of failure); idly, i.e. without reason (or effect)
KJV Usage: without a cause, (in) vain(-ly)
UBS Dictionary of the Greek New Testament
advb.
89.20 · Relations · Cause and/or Reason
without cause, without reason, for no reason pertaining to there being no cause or legitimate reason
89.54 · Relations · Result
in vain, to no avail, with no result pertaining to being without any result In a number of languages an expression such as ‘to be without results’ may be rendered as ‘will accomplish nothing’ or ‘will be as though it had never happened.’
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
εἰκῆ (1, WH Re εἰκῇ ; ef. Bttm. Ausf. Spr. ii. p. 342; B. 69 (61); [W.$5,4e.; Jelf § 324 Obs. 6; Kuhner $336 Anm. 7; esp. Etym. Magn. 78, 26 sq.; and reff. s. v. I, 17), adv.; in Grk. writ. fr. Aeschyl. down; 1. inconsiderately, without purpose, without just cause : Mt. v. 22 RGTrbr.; Ro. xiii. 4 (i.e. ‘not to hide it in the seabbard, but to draw it’ Fritzsche); Col. ii. 18. 2. in vain; without success or effect: 1 Co. xv. 2; Gal. iii. 4; iv. 11. [From Xenophon, Aeschyl. down.]
Mounce Concise Greek Dictionary
εἰκῇ eikē 6x
without plan or system; without cause, rashly, Col. 2:18; to no purpose, in vain, Rom. 13:4; 1 Cor. 15:2; Gal. 3:4 (2x); 4:11*
Abbott-Smith Greek Lexicon
εἰκῇ (-ῆ, Rec., as in cl.), adv.,
[in LXX: Pr 28:25 (εἰκῇ)* ;]
without cause or reason: Mt 5:22 (E, mg.), Col 2:18 (ICC).
vainly, fruitlessly, to no purpose: Ro 13:4, I Co 15:2, Ga 3:4 4:11, Col 2:18.†
Moulton & Milligan — Vocabulary of the Greek NT
εἰκῆ is found in P Lips I. 104*® (B.c. 96-5) ( = Witkowski?, Ρ- 118) εἰκῆ ἐφ᾽ ἁλλαχῆ βαδίζετε. Witkowski notes that the meaning may be either ‘‘audacter” or ‘ frustra”’: cf. P Leid G® (B.c. 181-145) εἰκῆ Kal ὡς ἔτυχεν, where the editor translates “‘temere et forte.” For εἰκαῖος see P Ryl IL. 235" (ii/A.D.) ἀλλὰ οὐ πρώτως σου τὸ εἰκαῖον μανθάνομεν, ““ but it is not the first time that we learn your heedlessness” (Edd.). Since εἰκῆ is an adverbial dat. like ἰδίᾳ, δημοσίᾳ, and the ancient inscriptional evidence shows some confusion, we cannot be certain whether to write εἰκῆ or εἰκῇ: see Moulton Gr. ii. ὃ 66.
Liddell-Scott-Jones — Greek-English Lexicon
εἰκῇ (eikē) — in vain. εἰκῇ, without plan or purpose, at random, at a venture, [Refs 6th c.BC+]
II. in vain, [NT+1st c.BC+]
III. slightly, moderately, ἀγγεῖα εἰ. πεπυρωμένα [Refs 2nd c.BC+]