The Greek aprositos means unapproachable or inaccessible — that which cannot be approached or accessed. It combines a (negative prefix) with prositos (approachable), forming a word of absolute inaccessibility.
Aprositos appears once in the New Testament in 1 Timothy 6:16, describing the light in which God dwells — phos oikón aprositos — 'unapproachable light.' This is one of the Bible's most striking affirmations of divine transcendence. God in His essential being is beyond human approach. No one has seen or can see Him (1 Timothy 6:16). Yet this same God, in Christ, has bridged the gap — the veil torn at the cross (Matthew 27:51) opened the way into the holy of holies (Hebrews 10:19-20). The aprositos God became accessible through the incarnation and atonement.