The word "un-wind" typically refers to the act of relaxing or de-stressing. Its antonyms, therefore, would be words that imply tension or stress. Some examples include "tense," "uptight," "anxious," "nervous," "frazzled," and "stressed." These words describe a state of mental or emotional discomfort, which is the opposite of the relaxed state that "un-wind" suggests. Using precise antonyms can help to create tension in a scene or story, highlighting the contrast between characters or settings. It also allows for more vivid and effective description, making a piece of writing feel more immediate and engaging.