Orexis (ὄρεξις) means desire, longing, appetite — the reaching out of the soul. Used in Greek philosophy for the appetitive faculty. Appears once in the NT, negatively.
Romans 1:27 describes those 'inflamed with lust' — disordered orexis. Paul's point is not primarily about sexuality but about the corruption of all appetite when God is rejected. All desire was created good — for God, beauty, connection, nourishment. Separated from God, desires become consuming and destructive. The gospel restores orexis to proper order: 'Delight yourself in the LORD, and he will give you the desires of your heart' (Psalm 37:4).