Definitions of Religion

Merriam Webster: from Latin religion-, religio
supernatural constraint, sanction, religious practice,
perhaps from religare to restrain, tie back -- more at RELY

1 a : the state of a religious <a nun in her 20th year of
religion> b (1) : the service and worship of God or the
supernatural (2) : commitment or devotion to religious faith or
observance
2 : a personal set or institutionalized system of religious
attitudes, beliefs, and practices
3 archaic : scrupulous conformity : CONSCIENTIOUSNESS
4 : a cause, principle, or system of beliefs held to with ardor
and faith

Latin root religio: "to join again", to "reconnect"
classical Latin: awe for the gods and concern for proper ritual (Aeneas)