Reattain means to gain back or regain something that was lost. The antonyms for this word would be to lose or forfeit, which means to let go of something that was previously obtained. Another antonym for reattain could be to miss or fail, meaning to not achieve a goal or regain something that was lost. Additional antonyms include surrender, abandon, and relinquish, which all imply giving up ownership or control of something. In contrast, attain, achieve, and acquire are synonyms for reattain, meaning to gain, obtain, or reach a goal or desired outcome.