I tend to use the word "
spiritual" in the same way St. Paul employed it in his epistles, since he was the first person to coin the term
pneumatikos (spiritual) from the Greek
pneuma. This was subsequently translated into Latin as
spiritualitas and ultimately English as "spiritual" and "spirituality".
Since Paul effectively came up with the idea, I feel obliged to accept his interpretation.
Here's how he used it:
“The natural (psychikos) man does not accept the things of the Spirit (Pneuma) of God: they are foolishness to him and he cannot understand them, for they must be judged spiritually. But the spiritual (pneumatikos) man judges all things and is judged by no one"
(1 Corinthians 2:14-15)
The adjective
psychikos in the New Testament refers to the
psyche that is, the sensual life and the natural, physical body subject to perishableness, death and decay.
Pneumatikos by contrast refers to a new, spiritual life that is immaterial in origin check out the meaning at
infospiritual, imperishable and not subject to death or decay.
Elsewhere in 1 Corinthians, Paul uses
pneumatikos in the sense of the spiritually mature in this world (2:15; 3:1; 14:37; cf. Gal. 6:1). The person who is not
pneumatikos is described as being 'fleshly' (
sarkinos).