The antonyms for the phrase "being in possession of" includes not having, lacking, missing, devoid of, and being without. These words denote a state of not having something or being deprived of something that could be vital. Lacking suggests the absence of something necessary or desirable. Missing suggests the absence of something required, expected or wanted. Devoid of implies a total lack or absence of something valuable or essential. Being without means not having or existing without something that is considered essential, necessary or desirable. These antonyms imply a lack of control or ownership over something, and they highlight the importance of being responsible for the things we possess.