analgesia

n. absence of pain, insensitivity to pain

An analgesic (colloquially known as a painkiller) is any member of the diverse 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 nonsteroidal anti-inflammatory drugs (NSAIDs) such as the salicylates, narcotic drugs such as morphine, synthetic drugs with narcotic properties such as tramadol, and various others. Some other classes of drugs not normally considered analgesics are used to treat neuropathic pain syndromes; these include tricyclic antidepressants and anticonvulsants.
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Analgesia /an·al·ge·sia/ 1. absence of sensibility to pain. 2. the relief of pain without loss of consciousness. [more]Analgesia - Community and Resources

Noun
1. absence of the sense of pain without loss of consciousness
(hypernym) physiological state, physiological condition

n. analgesia, absence of pain, insensitivity to pain