Definition from Wiktionary, the free dictionary
Etymology 1 
Form of the verb accidō (“fall upon; befall”).
- first-person singular imperfect active subjunctive of accidō
- "I would fall down, I would fall upon, I would fall near; I would descend"
- "I would happen (to), I would take place, I would occur, I would befall"
Etymology 2 
Form of the verb accīdō (“fell, cut down; use up; impair”).
- first-person singular imperfect active subjunctive of accīdō
- "I would begin to cut into, I would begin to cut through, I would fell, I would cut down"
- "I would use up, I would consume, I would diminish"
- "I would impair, I would weaken, I would shatter"