Final answer:
Objective information in medical terms that can be observed and usually measured is known as a sign, which is different from a symptom that is a subjective experience of the patient.
Step-by-step explanation:
Objective information that can be observed and usually measured is called a sign. A sign is something that can be directly observed by someone other than the patient and is typically measurable, such as a rash, a fever, or the presence of antibodies in a patient's serum. This is in contrast to a symptom, which is a subjective experience felt by the patient, like pain or nausea. Medical professionals utilize signs, along with symptoms, to diagnose diseases and prescribe treatment. They can use tools such as the Wong-Baker Faces pain-rating scale to quantify subjective symptoms and provide a more objective assessment.