Stubborn rejection refers to a persistent refusal to accept or acknowledge something. Synonyms for such a phrase could be obstinate denial, adamant refusal, unwavering rejection, unyielding dismissal, or determined repudiation. Some other related phrases include stiff-necked opposition, bullheaded objection, and resolute dissent. Regardless of the phrasing used, the connotation remains that the individual or group in question is unwilling to change their stance on a particular issue. This could be due to personal beliefs, biases, or even a lack of understanding. However, these synonyms emphasize the strength and persistence of the rejection, making it clear that it is not a mere passing disagreement or casual disagreement.