IPA: //ʌnˈspɪrɪtʃuəl//
KK: /ʌnˈspɪrɪtʃuəl/
Not related to spiritual matters; lacking in spiritual qualities or significance.
He felt that the unspiritual environment of the office was affecting his creativity.
Unspiritual → It is formed from "un-" (meaning not) and "spiritual" (from Latin "spiritualis", meaning relating to the spirit). The word "unspiritual" means not relating to the spirit or lacking spiritual qualities.
Think of 'not' ('un-') relating to the 'spirit' ('spiritual') — that's why unspiritual means lacking spiritual qualities.