Spirit is the nonphysical aspect of a person, and in Christian usage it is also the name of the third person of the Trinity. The same word does double duty, and the overlap is deliberate.

In the Hebrew Bible the ruach of God is the breath or wind that brings life, inspires prophets, and empowers leaders. In the New Testament the Holy Spirit descends at Jesus’ baptism, is poured out at Pentecost, and indwells believers as the down payment of the age to come. The Spirit convicts, comforts, guides, and distributes gifts for the common good. Christian theology insists that the Spirit is not an impersonal force but a personal presence, equal in divinity with the Father and the Son.

Outside Trinitarian faith the word still carries weight. Many cultures speak of the human spirit as the seat of courage, resilience, or creativity. Some philosophical traditions distinguish spirit from soul, reserving the former for the highest, most Godward aspect of the person. In ordinary speech a person of spirit is someone who refuses to be crushed.

Whether referring to the divine or the human, spirit names the dimension of reality that cannot be weighed or measured yet is known by its effects.