Happy Memorial Day! The word memorial is obviously an adjectival form of the word memory, which somewhat less obviously comes from the Anglo-Norman word memoire. Through Old French, this derives from the Latin word memoria, which in addition to still meaning "memory" also meant "record" and "method of remembrance". The root here is memor, meaning something like "mindful", and this comes from Proto-Indo-European smer, meaning the verb "remember". This is a pretty standard word origin, but the best part of this etymology is all of its relatives and other assorted linguistic nuggets. It helps form the words commemorate, remember, mourn, memoir, memo, memorandum, and much more. Since peak usage in the 1760s, utilization of the word memorial has decreased over time, but Google searches of the world always peak in late May. I couldn't find stats for memorial, but memory is the 894th most common word in the English language. It's a pretty large difference; memory is used 0.0085% of the time while memorial only makes up 0.0006% of all words used.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.