If something is fleeting or lasts a short time, it is transitory. Your boss declared the company's restructuring to be transitory, and promised that the company would emerge stronger and better than ever.
The adjective transitory describes something that is fleeting, temporary, or brief. Even a transitory storm that passes quickly can get you drenched. Consider it an honor to be on the transitory team that helps the president make a smooth transfer of power. When you met your first love, your parents thought that the relationship was transitory — but fifty years later, you're still married!