Dom 
(d
ŏm)
n.1. (also dōɴ) Used formerly as a title for male members of Portuguese and Brazilian royalty, aristocracy, and hierarchy, preceding the given name.
2. Roman Catholic Church Used as a title before the names of Benedictine and Carthusian monks in major or minor orders.
[Portuguese, from Latin dominus, lord, master; see dem- in the Appendix of Indo-European roots.]