The antonyms for the word "glitziest" are plain, modest, simple, unadorned, unostentatious, unpretentious, dull, and ordinary. While glitzy means showy and extravagant, its antonyms mean the opposite. Plain describes something that is unadorned and undecorated. Modest refers to something that is not excessive or showy. Simple means something that is not complex or intricate. Unadorned and unostentatious both imply a lack of embellishment or decoration. Unpretentious suggests modesty and lack of pretense. Dull and ordinary are self-explanatory, indicating that something is lacking in sparkle and interest. All these antonyms are useful in describing people, places or things that are not flashy or overtly showy.