the.com/misdeed

means A wrong or bad act someone has committed — a sin or crime stripped down to its plain, unglamorous name.

from Straightforward Old English carpentry: 'mis-' (wrongly, badly) bolted onto 'deed' (a thing done). It's been in the language since Old English as 'misdæd,' making it one of the plainer, older members of the mis- family (alongside misdo, misgiving), never dressed up in Latin or French finery like 'transgression' or 'felony.'