Is there a word for someone who speaks before they think

Well as the title says, is there a word for a person who talks before they think? And if it is, whats the word and what's the antonym? I need to know this for to characters in a novel. Thank you in advance.


Solution 1:

loose-tongued adj

careless or irresponsible in talking.

It seems 'tight-lipped' can be used as an antonym of 'loose-tongued'.

tight-lipped adj

Reluctant to speak; close-mouthed.