Re-weigh means to weigh again, which implies that the original weight was inaccurate or incomplete. Its antonyms would be the terms that mean the opposite of re-weighing, such as measure, estimate, gauge, approximate, or evaluate. For example, if you measure something, you are taking its weight, size, or quantity for the first time. Likewise, if you evaluate a product or a piece of information, you are making a judgment or analysis based on different variables. The antonyms for re-weigh would depend on the context and the type of measurement involved. However, they all suggest different degrees of certainty, precision, and accuracy in the assessment.