Word parts accidental + -ly Pronunciation IPA (key): /ˌæksəˈdɛnt(ə)li/ Audio (US)(file) Adverb Positive accidentally Comparative more accidentally Superlative most accidentally If something happens accidentally, it happens without a plan, and is usually a bad thing. Sorry, I accidentally dropped it. Related words accidental accident Wikiwand - on Seamless Wikipedia browsing. On steroids.