1 a the study of theistic (esp. Christian) religion. b a system of theistic (esp. Christian) religion. c the rational analysis of a religious faith.
2 a system of theoretical principles, esp. an impractical or rigid ideology.
Derivatives:
theologist n. theologize v.tr. & intr. (also -ise).
Etymology: ME f. OF theologie f. L theologia f. Gk (as THEO-, -LOGY)
Useful english dictionary. 2012.