Lexical Definition

‎ἄλογος‎ álogos (al'-og-os) unreasonable ^G:A
from ‎Α‎ (as a negative particle) and ‎λόγος‎

brute, unreasonable.

• irrational

Abbott-Smith

ἄ-λογος, -ον [in LXX: Ex 6:12 (שָׂפָה עָרֵל), Nu 6:12 (נָפַל), Jb 11:12, Wi 11:15, 16, IV Mac3*;]
1. without reason, irrational: ζῷα, II Pe 2:12, Ju 10.
2. contrary to reason: Ac 25:27 (v. MM, VGT, s.v.).†

Abbott-Smith References

Liddell-Scott-Jones

ἄλογος, ον,

without λόγος, hence,

__I speechless, [Refs 5th c.BC+]. adverb -ως without speech, [Refs 5th c.BC+] —ἄ. ἡμέρα, = Latin dies nefastus, on which no business may be done, [Refs 2nd c.AD+]
__I.b lacking in eloquence, [LXX]
__I.2 inexpressive, [Refs 5th c.BC+]; unutterable, ={ἄρρητος}, [Refs 5th c.BC+]
__II unreasoning, ἡδονή, ὄχλος, etc., [Refs 5th c.BC+]brutes, animals, [Refs 5th c.BC+]; especiallyin late Greek, ἄλογον, τό, = horse, [Refs 2nd c.AD+]
__II.2 not according to reason, irrational, ἄ. δόξα, opposed to ἡ μετὰ λόγου δ., [Refs 5th c.BC+]; ἀλόγῳ πάθει τὴν ἄ. συνασκεῖν αἴσθησιν, instinctive feeling, in appreciating works of art, [Refs 1st c.BC+]
__II.3 contrary to reason, absurd, [Refs 5th c.BC+]; unaccountable, unintelligible, [Refs 5th c.BC+]; unfit, unsuited to its end, [Refs 5th c.BC+]; groundless, [Refs 2nd c.BC+]. adverb most frequently in this sense, [Refs 5th c.BC+]: superlative -ώτατα[Refs 1st c.BC+]
__III without reckoning:
__III.1 not reckoned upon, unexpected, [Refs 5th c.BC+]
__III.2 not counted, null and void, ἡμέραι[LXX]
__III.3 active, not having paid one's reckoning, of an ἐρανιστής, [Refs]
__IV of magnitudes, incommensurable, περὶ ἀλόγων γραμμῶν, title of work by [Refs 4th c.BC+]
__IV.2 in Rhythm, irrational, of feet or syllables whose time-relations cannot be expressed by a simple ratio, χορεῖος[Refs 4th c.BC+]; ἄλογοι, i.e. συλλαβαί, [Refs 1st c.BC+]:—of the pulse, unrhythmical, [Refs 3rd c.BC+]

_{LSJ Scripture Refs: LXX.Exod.6.12 ☩ LXX.Num.6.12}