Antonyms for the phrase "dressed to the teeth" can be described as wearing inappropriate or immodest attire. It includes words like underdressed, slovenly, shabby, disheveled, untidy, scruffy, and dowdy. A person who is underdressed may appear casual or unkempt in formal or upscale settings, while a slovenly or shabby appearance may indicate neglect or lack of care in their clothing. A disheveled or untidy look may suggest a lack of attention to one's appearance, while a scruffy or dowdy appearance may indicate outdated or unfashionable choices. Regardless of the antonym used, it is advisable to dress appropriately for the occasion to leave a positive impression.