requiem

Concise Oxford English Dictionary © 2008 Oxford University Press:
requiem /ˈrɛkwɪəm, -ɪɛm/

▶noun

• 1 (especially in the Roman Catholic Church) a Mass for the repose of the souls of the dead.

• 2 a musical composition setting parts of such a Mass.

• 3 an act or token of remembrance.

– origin ME: from L. (first word of the Mass), accusative of requies ‘rest’.