Apeimi means to be away from, absent, or not present. Composed of apo (away from) and eimi (to be), it describes physical absence. Paul uses it frequently in his letters to contrast his absence in body with his presence in spirit, and to address how his conduct was the same whether present or absent.
Paul's use of apeimi (absent) in 2 Corinthians and Philippians reflects his theology of integrity — he was the same person whether he could be seen or not. Authentic Christian character does not change based on observation. The believer who lives as though always in the presence of God will be the same person absent or present, watched or unwatched.