The phrase "crit partners" is a shorthand way of saying "critique partners." It refers to individuals who exchange and give constructive feedback on each other's work, such as writing or artwork, to help improve it. Full definition
I'm testing my stories through crit partners and beta readers. (writerunboxed.com)
I guess the only difference between betas and critique partners are betas read the entire manuscript at once, and crit partners go through chapter by chapter with you. (tamerietherton.com)