Subtly is a word often used to describe something that is not overtly or immediately noticeable, often implying a sense of delicacy or nuance. Synonyms for subtly include understated, subdued, muted, faint, gentle, subdued, muted, slight, soft, and delicate. Other synonyms can include nuanced, refined, unobtrusive, discreet, or understatedly. Each of these words provides a slightly different emphasis on the way in which something is not immediately noticeable to the senses, but rather requires some attention or care to perceive its presence. Overall, these synonyms help to convey the subtlety and nuance that is often present in the world around us.