comma splice

“A comma splice occurs when two independent clauses are connected with only a comma.” (Purdue Owl)

“Two or main clauses joined only with a comma: I came, I saw, I conquered.” (Everyone's An Author with Readings 989)

“English teachers refer to sentences where clauses requiring some stronger punctuation are instead lightly pasted together with a comma as 'comma splices.' Here’s an example: 'He brought her a dozen roses, he had forgotten she was allergic to them.' In this sentence the reader needs to be brought up sharply and reoriented mid-sentence with a semicolon; a comma is too weak to do the trick. Here's a worse example of a comma splice: 'It was a beautiful day outside, she remembered just in time to grab the coffee mug.' There is no obvious logical connection between the two parts of this sentence. They don't belong in the same sentence at all. The comma should be a period, with the rest being turned into a separate sentence” (Common Errors in English Usage)