The Greek adjective amoomos (ἄμωμος) means without blemish, faultless, or spotless. It is the cultic term for animals suitable for sacrifice — those without physical defect — applied in the New Testament to Christ and to the character God calls believers toward.
The Levitical requirement for sacrifice was an animal 'without blemish (amoomos)' — physical perfection signifying the need for a perfect offering. Peter applies this directly to Christ: 'a lamb without blemish (amoomou) or defect' (1 Peter 1:19). Paul in Ephesians 1:4 declares that God chose believers 'to be holy and blameless (amoomous) in his sight' — the goal of election is moral conformity to Christ. Revelation 14:5 describes the 144,000 as 'without fault (amoomoi)' before God's throne. What was required of the sacrifice is now gifted to the worshiper through the perfect Sacrifice.