Undrooping is a word that typically refers to something that doesn't droop or hang down. However, there are a variety of other words that can be used to describe this same concept. For example, a similar word might be "upright," which implies that something is standing up straight and not slouching or sagging. Other synonyms might include "perky," "erect," or "stiff," all of which connote a sense of stiffness or rigidity in an object or structure. Ultimately, the choice of word will depend on the context of the specific sentence or phrase in which it is being used, but there are plenty of options available to those looking for alternatives to "undrooping".