Lexical Definition

‎πλεονεκτέω‎ pleonektéō (pleh-on-cek-teh'-o) to exploit ^G:V
from ‎πλεονέκτης‎

get an advantage, defraud, make a gain.

• to be covetous, i.e. (by implication) to over-reach

Abbott-Smith

πλεονεκτέω, -ῶ (< πλεονέκτης, q.v.), [in LXX: Hb 2:9, Ez 22:27 (בּצע), Jg 4:11 B*;]
1. intrans., to have more, to have an advantage (cl., c. gen. pers.).
2. Trans., in late writers (v. M, Pr., 65), to overreach, defraud: c. acc. pers., II Co 7:2 12:17, 18; ἐν τ. πράγματι, I Th 4:6 (v. M, Th., in l.); pass., II Co 2:11 (as also in cl.; v. LS, s.v.).†

Abbott-Smith References

Liddell-Scott-Jones

πλεονεκτέω-έω,

future -ήσω[Refs 5th c.BC+]:—Prose Verb, have or claim more than one's due, mostly in bad sense, to be greedy, grasping, [Refs 5th c.BC+]

__2 also, gain or have some advantage, without any bad sense, δυνάμει τινὶ π. [Refs 5th c.BC+]; opposed to ἐλαττοῦσθαι, [Refs 5th c.BC+]
__3 with genitive of things, have or claim a larger share of than others, τῶν ὠφελίμων [Refs]; τοῦ ἡλίου, τοῦ ψύχους, τῶν πόνων, [Refs 5th c.BC+]; δόξης, χάριτος, [Refs 4th c.BC+]
__II with genitive person, have or gain the advantage over, τῶν ἐχθρῶν [Refs 5th c.BC+]; τινι in a thing, [Refs 5th c.BC+]; also π. τῶν νόμων gain at the expense of the laws, [Refs]; τῆς ὑμετέρας π. εὐηθείας take advantage of your simpleness, [Refs 4th c.BC+]
__II.2 later with accusative person, get or have the advantage over, [Refs 1st c.BC+]: usually in bad sense, overreach, defraud, πλεονεκτέωεῖν μηδένα [NT+4th c.BC+]: in early writers only passive in this sense, ὑπό τινων [Refs 5th c.BC+]; πλεονεκτέωεῖσθαι χιλίαις δραχμαῖς to be defrauded in or of [πλεονεκτέωεῖσθαι">Refs 5th c.BC+] is impersonal, to be an act of πλεονεξία.
__II.3 passive, to be surpassed, excelled, τινι [Refs 2nd c.AD+]

_{LSJ Scripture Refs: 1Thess.4.6 ☩ 2Cor.7.2}