Not too many generations ago, any child privileged enough to attend school beyond the age of seven or so studied Latin. A vestige of what was once a universal educational practice can be found in the use of these three Latin terms used by English speakers:
I’ve seen mea culpa misspelled as “mia culpa,” and in memoriam misspelled as “in memorium.” As for R.I.P. seen in cartoon drawings of tombstones and on Halloween-related decorations, many speakers are unaware that the initials R.I.P. stand for a Latin phrase.
mea culpa [mā’ə kool’pə]:”my fault.” The expression is part of a prayer of repentance, but it is often used in a secular context to mean “it’s my fault.” I know a classics professor who likes to translate it as “my bad!” If you feel really guilty, you can say, “Mea culpa, mea culpa, mea MAXima culpa!” The misspelling “mia” probably results from saying /mee-uh/ instead of /may-uh/.
The Latin word culpa, “crime, fault, blame,” is at the root of several English words: culpable, culpability, culprit, exculpate, and exculpatory.
in memoriam: “in memory of.” Tennyson named his long poem to the memory of his friend Hallam In Memoriam.
English words from Latin memor, “mindful, remembering,” include: memory, memorable, immemorable (“not worth remembering”), immemorial (“ancient beyond memory”), memorize, commemorate, and commemoration.
R.I.P., the initial letters of the Latin phrase Requiescat in pace: “may he/she rest in peace.” As it happens, the English translation “Rest in peace” gives the same initial letters of the Latin original.
Latin requies, “rest, repose,” gives us the word requiem, Capitalized, a Requiem is a “Mass for the repose of the soul of the dead.” A generalized sense of requiem is any formal tribute to a departed soul.
English words that derive from the same Latin source as requiem are quiet, quiescent, quiescence, and inquiet.