The modern use, since the late 17th century, suggests a minor kind of aberrant behaviour, often without intentional ill-will. But when the word first entered English, around 1300, it was quite the reverse. When Joan harangues her captors with "mischief and despair Drive you to break your necks" (Henry VI Part 1, V.iv.90), she is using the word in its original sense of "catastrophe, calamity". And when Romeo says "O mischief, thou art swiftTo enter in the thoughts of desperate men" (Romeo and Juliet, V.i.35), "desperate" hints at the stronger meaning required here too:
"wicked action, harmful scheme". Similarly, Talbot talks of "hellish mischief" (Henry IV Part 1, III.ii.39) and Aaron of laying "Complots of mischief" (Titus Andronicus, V.i.65). A third sense, "disease, ailment", is heard when Don John tells Conrade: "thou ... goest about to apply a moral medicine to a mortifying mischief" (Much Ado About Nothing, I.iii.12).
David Crystal is author, with Ben Crystal, of Shakespeare's Words, published by Penguin