Tom Arnold Blasts Chuck Lorre as 'Terrible Human' and 'Bitter Hack'

Tom Arnold went off with a big bang on Chuck Lorre ... calling him a terrible guy and a total hack who looked like a "sad clown" when he was axed from "Roseanne."

The actor and comedian hopped on social media to bash Chuck ... saying the guy might think he's beloved like fellow sitcom giant Norman Lear, when in fact he's "a terrible human ... who lies every time he opens his mouth."

He says Chuck might trash President Donald Trump -- whom Tom has no love for -- but he's really just like the controversial prez ... adding Chuck is a "bitter hack" who thinks his vanity cards are so dang witty when they're really not.

Tom says Chuck made a ton of money off women ... and Charlie Sheen -- who Tom points out is sober now that he's far away from Chuck. Tom says these people have made Chuck millions, then he trashes them for no darn reason.

He finishes off his post by adding, "I wish everyone could've seen his arrogant, sad clown face the day Roseanne made me fire him."

If you don't know ... Chuck was a writer on "Roseanne" during seasons 3 and 4 of the hit show -- contributing in some capacity to 12 episodes. The circumstances of his leaving the show are debated ... with Roseanne and Tom each claiming they were the one who fired him -- while Chuck claims he left at the end of his contract.

Tom's online rant seems to be a response to Chuck's new book "Sitcom: A Memoir" ... in which he's taken shots at Anna Faris -- and even claimed Tom forced "Roseanne" writers to put his name on scripts he didn't contribute to.

We've reached out to Chuck about Tom's diatribe ... so far, no word back.