panacea (n.)

"universal remedy," 1540s, from Latin panacea, a herb (variously identified) that would heal all illnesses, from Greek panakeia "cure-all," from panakēs "all-healing," from pan- "all" (see pan-) + akos "cure," from iasthai "to heal" (see -iatric). Earlier in English as panace (1510s).