The antonyms for the word "counter signature" refer to the situations where a second signature is not required. Some of the antonyms are "single signature," "unilateral agreement," and "unilateral decision." These words denote cases where only one person's endorsement or approval is necessary. Furthermore, "unilateral action" and "independent approval" are other antonyms that convey the idea of self-reliance and the absence of the need for a second signature. In sum, the antonyms of "counter signature" are related to situations where a single signature, decision or action is sufficient, indicating the absence of the need for co-signers or counterparts in any agreement or act.