An analgesic (also known as a painkiller) is any member of the group of drugs used to relieve pain (achieve analgesia). The word analgesic derives from Greek an- ("without") and algos ("pain").
Analgesic drugs act in various ways on the peripheral and central nervous systems; they include paracetamol ...
(para-acetylaminophenol, also known in the US as acetaminophen),
the non-steroidal anti-inflammatory drugs (NSAIDs) such as the salicylates,
and opioid drugs such as morphine and tramadol.