τέλειος
téleios · adjective · “mature, complete, perfect”
Teleios means complete, mature, or whole — not flawlessness, but a full, finished kind of life. It is the goal Jesus and the apostles set before the believer.
Greek perfection (teleios) is less about moral spotlessness than about reaching the end (telos) something was made for — fully grown, complete, finished. A teleios person is a mature, whole person.
When Jesus says “you therefore must be perfect, as your heavenly Father is perfect,” he calls his disciples into a love as complete and undivided as his Father’s — not into anxious self-improvement. James and Paul use the same word for spiritual maturity.
Definition: complete (in various applications of labor, growth, mental and moral character, etc.); neuter (as noun, with G3588 (ὁ)) completeness
KJV usage: of full age, man, perfect
Reference gloss from Strong's Concordance (1890, public domain).
Original BibleDawn word study. Original-language data and the public-domain Strong's (1890) gloss are referenced; see sources.