Lexical Definition

‎ἁπλότης‎ haplótēs (hap-lot'-ace) openness ^G:N-F
from ‎ἁπλοῦς‎

bountifulness, liberal(-ity), simplicity, singleness.

• singleness, i.e. (subjectively) sincerity (without dissimulation or self-seeking), or (objectively) generosity (copious bestowal)

Abbott-Smith

ἀπλότης, -ητος, ή (< ἁπλοῦς), [in LXX: II Ki 15:11 (תֹּם), I Ch 29:17 (לֵבָב ישֶׁר, ἁ. τῆς καρδίας, cf. Col 3:22, where v. Lft.), Wi 1:1, al.;]
simplicity, sincerity: Ro 12:8, II Co 11:3, Eph 6:5, Col 3:22; as manifested in generous, unselfish giving, liberality, graciousness: II Co 8:2 9:11, 13 (v. ICC, Ro., 12:8; Hort, Ja., 1:5, and v.s. ἁπλῶς).†

Abbott-Smith References

Liddell-Scott-Jones

ἁπλότης, ητος, ἡ,

singleness, τῆς φωνῆς[Refs 4th c.BC+]

__II simplicity, πόλεως[Refs 5th c.BC+]
__II.2 of persons, simplicity, frankness, sincerity, [NT+5th c.BC+]
__II.3 open-heartedness: hence, liberality, [Refs]

_{LSJ Scripture Refs: 2Cor.11.3}