1. A characteristic sign or indication of the existence of something else.
2. A sign or an indication of disorder or disease, especially when experienced by an individual as a change from normal function, sensation, or appearance.
3. Etymology: from about 1541, earlier sinthoma (1398), from Medieval Latin (c.700-c.1500) sinthoma, "symptom of a disease"; from Late Latin (c.300-c.700) symptoma, from Greek symptoma (genitive symptomatos), "a happening, an accident, a disease"; from the stem of sympiptein, "to befall"; from syn-, "together" + piptein, "to fall". Spelling was altered in English by Middle French (c.1400-c.1600) and Late Latin forms.