adjective
Definition: Describing someone who is excessively worried about their health and often believes they are ill, even when they are not.
Example: She tends to be a hypochondriac, always fearing she has a serious illness.
noun
Definition: A person who is excessively worried about their health and often believes they are sick, even when there is no real medical issue.
Example: Despite being perfectly healthy, she often acts like a hypochondriac, constantly fearing she has serious illnesses.