From Longman Dictionary of Contemporary Englishmatinsmat‧ins, mattins /ˈmætənz $ ˈmætnz/ noun [uncountable] RRCthe first prayers of the day in the Christian religion SYN morning prayer
Examples from the Corpus
matins• But of course, though not before ten-thirty as the Archdeacon was taking a matins for some one on holiday.• Not the right frame of mind for matins.Origin matins (1200-1300) Old French matines, from Latin matutinus “of the morning” 