noun
memorial mass; requiem mass
Specifically a Catholic memorial mass for the deceased.
先週、教会で祖父の追悼ミサが行われた。
A memorial mass for my grandfather was held at the church last week.
ミサ is a general Catholic mass, while 追悼ミサ specifically refers to a mass for the deceased.
Compound of 追悼 (tsuitō, 'mourning') and ミサ (misa, 'mass', from Latin 'missa').