Check out On, By, or -ly? by rogersgeorge. Here is an excerpt:
This post has to do with three usages of the root word accident that make it into an adverb.
- If you ain’t got no good taste, use “on accident.” See the comic below, though the comic itself is worth subscribing to if you’re an intellectual.
- If you’re normal, use “by accident.”
- If you want to be…
The full article is available here.
