The word "un-obtrusive" denotes something that is discreet or inconspicuous. Its antonyms are words that describe something that is attention-grabbing or prominent. One antonym for un-obtrusive is "obtrusive," which means something that is noticeable or intrusive. Other antonyms include "ostentatious," which denotes showiness or excessive display, "flamboyant," which suggests striking or bold style, and "conspicuous," which refers to something that is easily seen or noticed. These words all describe something that is the opposite of un-obtrusive and are useful for describing things that are meant to be attention-grabbing or showy.