Bryan Garner on mischievous:
mischievous /MIS-chә-vәs/ is so spelled. *Mischievious is an impishly common misspelling and mispronunciation /mis-CHEE-vee-әs/.I always thought my eight-grade teacher was mispronouncing the word. She also mispronounced comfortable as /kәm-FORT-ә-bәl/. These mispronunciations came during spelling tests.
All OCA posts (Pinboard)
[I’ve substituted capitals for Garner’s bold.]