The term 'Altar Neighbor' is composed of three crossword solutions: APSE (4 letters), ARA (3 letters), and ALB (3 letters). APSE is an architectural term referring to a semicircular or polygonal recess in a church, usually at the east end, containing the altar. ARA is an abbreviation for the Latin phrase 'altare regale, ' which translates to 'royal altar.' ALB is an abbreviation for the Latin phrase 'alba vestis, ' which translates to 'white garment, ' and is a type of liturgical vestment worn by priests during Mass. Altar Neighbor is thus a term that refers to the architectural and liturgical elements that surround the altar in a church.