The word "over-using" can be defined as utilizing something excessively or beyond what is necessary. Oppositely, the antonyms for this word include "under-using," indicating the underutilization or inadequate use of something. Other antonyms for over-using can be "moderating" or "balancing," which refer to utilizing something in an appropriate or balanced quantity. Similarly, the term "rationing" may also be an antonym as it implies the controlled and limited use of a resource. Furthermore, "conserving" is another antonym which indicates the preservation of something by using it cautiously and responsibly. Overall, over-using has many antonyms that emphasize the need for using resources carefully and consciously.