Commeasuring is a term used to describe the act of determining the dimensions or size of an object. While there are no exact antonyms for this word, some phrases that could be used to convey the opposite meaning include "inexact measurement", "uncalculated dimensions", or "inaccurate size determination". Another option might be to use words like "approximation", "estimation", or "rough calculation" to express a lack of precision in measuring. Regardless of the specific phrasing, the antonyms of commeasuring all suggest a degree of uncertainty or imprecision in determining the dimensions or size of an object.