Mischievious

Trouble making. Mischievous. Devious. Naughty. This word began as an alternate pronunciation of mischievous but really has since branched off to become its own word, with its own spelling and pronunciation. People who use the word mischievious when speaking often also understand and recognize the word mischievous when spoken but often do not realize that the two were originally the same word. One might then consider them to simply be different words entirely (synonyms with confusingly similar spelling). According to Merriam-Webster's dictionary, there is evidence of the spelling "mischievious" going back to the 16th century. However, some people still view it simply as a mispronunciation and not as an actual word.