The crime of the century is not going to be a misdemeanor, but the history of the word itself may be more interesting than some of the crimes it describes. Looked at the right way, it could be construed to mean “misconducting animals by threatening them,” which might be poetic or might not, I haven’t decided.
Wiktionary gives the etymology of misdemeanor by breaking the word down into two pieces: “mis” (against, opposing) and “demeanor.” Demeanor comes from the latin de + mener + or. Mener was latin for “to conduct” or “to lead.” Mener may also have come from minari, which meant, “to threaten.”
The Online Etymology Dictionary has “demeanor” a little differently. They say that Middle English had a now-obsolete word demean, which meant “handle, manage, conduct” and by the 14th Century came to mean “behave in a certain way.” They trace this word by to the latin de + mener, just like Wiktionary does, and like Wiktionary, they trace that word to the latin “minare” meaning “to threaten,” in the way that a person might lead a herd of animals by threatening them.
According to Merriam Webster, the first known use of the word “misdemeanor” was in the 15th Century.