Definition of "matins"

This chant was sung in many cathedrals both at First Vespers and at Matins for Christmas Day. In Notre Dame and many other churches, however, it was only performed at First Vespers.

2017, Edward H. Roesner, editor, Ars antiqua: Organum, Conductus, Motet, Routledge, page 43

The monk must arise when the matins ring, / The abbot may sleep to their chime; / But the yeoman must start when the bugles sing / ’Tis time, my hearts, ’tis time.

1819, Jedadiah Cleishbotham [pseudonym; Walter Scott], Tales of My Landlord, Third Series. […], volumes (please specify |volume=I to IV), Edinburgh: […] [James Ballantyne and Co.] for Archibald Constable and Co.; London: Longman, Hurst, Rees, Orme, and Brown, […]; Hurst, Robinson, and Co. […]