Lexical Definition

‎ἄτομος‎ átomos (at'-om-os) instant ^G:A
from ‎Α‎ (as a negative particle) and the base of ‎τομώτερος‎

moment.

• uncut, i.e. (by implication) indivisible (an "atom" of time)

Abbott-Smith

** ἄ-τομος, -ον (< τέμνω), [in Sm.: Is 54:8 (MM, s.v.)*;]
indivisible; of time, ἄτομον, a moment: ἐν ἄ., I Co 15:52.†

Abbott-Smith References

Liddell-Scott-Jones

ἄτομος, ον,

uncut, unmown, λειμών[Refs 5th c.BC+]in lumps, [Refs 1st c.AD+]; ἄτομον, τό, ={ὑοσκύαμος}, uncertain in Ps.-[Refs 1st c.AD+]

__2 Grammars, of words, not compound, [Refs 1st c.BC+]
__II that cannot be cut, indivisible, γραμμαί[Refs 4th c.BC+]; especially of particles of matter, ἐτεῇ ἄτομα (i.e. σώματα) καὶ κενόν[Refs 4th c.BC+]
__II.2 of Time, οὐχ οἷόν τε εἰς ἀ. χρόνους διαιρεῖσθαι τὸν χρόνον[Refs 4th c.BC+]; ἐν ἀτόμῳ in a moment, [NT+2nd c.AD+]
__II.2.b metaphorically, infinitely small, διαφοραί[Refs 1st c.AD+]
__III in Logic, individual, of terms, [Refs 5th c.BC+]; of the εἶδος, [Refs 4th c.BC+]
__III.2 individual, [Refs]substantive ἄτομον, τό,[Refs 3rd c.AD+]
__III.3 of the summum genus, πρὶν εἰς τὰ ἄ. ἐλθεῖν[Refs 4th c.BC+]. adverb ἀτόμως, ὑπάρχειν immediately, without the intervention of a middle term, [Refs]

_{LSJ Scripture Refs: 1Cor.15.52 ☩ LXX.Isa.54.8}