The term "papertiger" refers to something that appears strong and powerful but is actually weak and ineffective. Some antonyms to this term could include words like 'strong', 'potent', 'formidable', 'invincible', 'robust', 'powerful', 'mighty', 'impenetrable', 'durable' and 'inviolable'. These words imply a sense of strength, power, and capability, which stands in stark contrast to the idea of something that is a 'papertiger'. By using these antonyms, one can convey a sense of true strength rather than just an appearance of strength. Therefore, these antonyms can be helpful to enhance writing or communication by utilizing more impactful words.