1540s, re-Latinized from sinthoma (late 14c.), from Medieval Latin sinthoma "symptom of a disease," altered from Late Latin symptoma, from Greek symptoma "a happening, accident, disease," from stem of sympiptein "to befall, happen; coincide, fall together," from assimilated form of syn- "together" (see syn-) + piptein "to fall," from PIE *pi-pt-, reduplicated form of root *pet- "to rush; to fly."
Spelling restored in early Modern English in part by influence of Middle French symptome (16c.). General (non-medical) use is from 1610s.