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