The antonyms for "accept offer" include decline, refuse, reject, spurn, or ignore. Each antonym implies a different level of rejection, ranging from a polite refusal to a complete dismissal. Decline indicates a polite rejection, whereas refuse and reject indicate a more straightforward rejection. Spurn connotes a feeling of contempt towards the offer or the person making it. Ignore implies a complete disregard for the offer, either intentionally or unintentionally. Choosing the right antonym depends on the situation and the relationship between the parties involved. Regardless of the antonym chosen, it indicates a lack of agreement or willingness to proceed with the offer.