Pertaining to the Spirit (of God), spiritual as opposed to natural or fleshly. Pneumatikos describes things, persons, and realities that belong to or are empowered by the Holy Spirit. It is Paul's key adjective for the new life in Christ versus the old life in the flesh.
Paul contrasts the pneumatikos person (Spirit-led) with the psychikos person (natural, unspiritual) in 1 Corinthians 2:14-15. Spiritual gifts, spiritual songs, spiritual blessings — all are empowered by the Spirit. The pneumatikos body of the resurrection (1 Corinthians 15:44) is not immaterial but Spirit-animated. 'Spiritual' in the NT always points to the Holy Spirit's activity, not to vague mysticism.