[muh-mawr-i-ter, -ter, -mohr-]
1. by heart; by memory.
2. involving or requiring memorization:
the memoriter aspects of a college course.
Memoriter is as rare in English as it is in Latin. In Latin memoriter is an adverb meaning “from memory, by personal recollection” and derives from the adjective memor “mindful, remembering” (also the source of the Latin noun memoria “memory”). All of the Latin words are (partially) reduplicated derivatives of the root mer- (and its variants) “to remember, care for.” This same reduplicated root is the source of Mímir (also Mim) “(the) Rememberer,” in Norse mythology a giant who guarded the well of knowledge and wisdom. The simple, unreduplicated root is the source of English “mourn” (from Old English murnan “to be anxious about, care for”). Memoriter entered English in the 17th century.
“The great objection to memoriter speaking is that it limits and handicaps the speaker.”
- Grenville Kleiser, Successful Methods of Public Speaking