The term "cosigns" refers to the act of endorsing, supporting, or approving something. Its antonyms would be words that have the opposite meaning, such as "opposes," "contradicts," "rejects," "denies," "disapproves," or "condemns." These antonyms indicate a lack of agreement, disfavor or disagreement with the action being taken, and highlight the absence of approval. The use of antonyms is crucial in effective communication as it helps to avoid confusion and clarify the intended message. In conclusion, by using antonyms, we can articulate our thoughts more accurately and avoid misunderstandings.