Lexical Definition

‎πταίω‎ ptaíō (ptah'-yo) to stumble ^G:V
a form of ‎πίπτω‎

fall, offend, stumble.

• to trip, i.e. (figuratively) to err, sin, fail (of salvation)

Abbott-Smith

πταίω, [in LXX chiefly for נגף ni.;]
1. trans., to cause to stumble (I Ki 4:3, cf. Deiss., BS, 681).
2. Intrans., to stumble. Metaph., in moral sense, Ro 11:11, Ja 2:10 3:2, II Pe 1:10.†

Abbott-Smith References

Liddell-Scott-Jones

πταίω,

[Refs 5th c.BC+]: future πταίσω [Refs 4th c.BC+]: aorist ἔπταισα [Refs 5th c.BC+]: perfect ἔπταικα [Refs 5th c.BC+] — passive, see #1:

__I transitive, cause to stumble or fall, σύνθεσιν ποτὶ ψεύδει [LXX+5th c.BC+]:—passive, to be missed, of things, [Refs 2nd c.AD+]; τὰ πταισθέντα failures, errors, [Refs 2nd c.AD+]; ἃ ἐπταίσθη his failures, [Refs 1st c.AD+]
__II intransitive, stumble, trip, fall, π. πρός τινι stumble against, fall over, π., ὥσπερ πρὸς ἕρματι, πρὸς τῇ πόλει [Refs 5th c.BC+]; πρὸς τὰς πέτρας conjecture in [Refs 5th c.BC+]; also π. περί τινι, μὴ περὶ Μαρδονίῳ πταίσῃ ἡ Ἑλλάς lest Hellas should get a fall over him, i.e. be defeated by him, [Refs 5th c.BC+]
__II.2 metaphorically, make a false step or mistake, [Refs 5th c.BC+]; ἐὰν πταίωσί τι when they make a blunder, of medical men, [Refs 4th c.BC+]; οὐκ ἐλάττω, ἐλάχιστα, τὰ πλείω π., [Refs 5th c.BC+]; τῇ μάχῃ, τοῖς ὅλοις, τοῖς πράγμασι, etc., [Refs 5th c.BC+]
__II.3 π. τῆς ἐλπίδος to be baulked of.. , [Refs 2nd c.AD+]
__II.4 ἡ γλῶττα π. stutters, [Refs 4th c.BC+]

_{LSJ Scripture Refs: LXX.1Kgs.4.3}