Something that a doctor notices when examining a patient. It may be obvious to the patient as well, such as a weak muscle, in which case it can also be a symptomA symptom is anything of which a patient complains with respect to his or her own body. It may also be obvious to an observer, for example a rash, but it may be entirely subjective, such as a pain somewhere or an emotional feeling.. It may, on the other hand, only be obvious to the trained eye, for example an altered body reflex.