The Collaborative International Dictionary of English v.0.48:

analgesic \an`al*ge"sic\ ([a^]n`[a^]l*j[=e]"z[i^]k or
   [a^]n'l*j[=e]"z[i^]k), a. [NL., fr. Gr. 'analghsi`a; 'an
   priv. + 'a`lghsis sense of pain.] (Med.)
   Serving to reduce the sensibility to pain without loss of
   consciousness. AS
   [PJC]

The Collaborative International Dictionary of English v.0.48:

analgesic \an`al*ge"sic\ ([a^]n`[a^]l*j[=e]"z[i^]k), n. [NL.,
   fr. Gr. 'analghsi`a; 'an priv. + 'a`lghsis sense of pain.]
   (Med.)
   a medication which serves to reduce the sensibility to pain
   without loss of consciousness. Aspirin and acetaminophen
   (paracetamol, trade name Tylenol) are commonly used
   non-prescription analgesics. --AS
   [PJC + AS]

WordNet (r) 3.0 (2006):

analgesic
    adj 1: capable of relieving pain; "the anodyne properties of
           certain drugs"; "an analgesic effect" [syn: analgesic,
           analgetic, anodyne]
    n 1: a medicine used to relieve pain [syn: analgesic,
         anodyne, painkiller, pain pill]

Moby Thesaurus II by Grady Ward, 1.0:

128 Moby Thesaurus words for "analgesic":
   Amytal, Amytal pill, Darvon, Demerol, Dolophine, H, Luminal,
   Luminal pill, M, Mickey Finn, Nembutal, Nembutal pill, Pyramidon,
   Seconal, Seconal pill, Tuinal, Tuinal pill, acetanilide,
   acetophenetidin, acetylsalicylic acid, alcohol, alleviating,
   alleviative, amobarbital sodium, anesthetic, anodyne, aspirin,
   assuasive, balmy, balsamic, barb, barbiturate, barbiturate pill,
   benumbing, black stuff, blue, blue angel, blue devil, blue heaven,
   blue velvet, calmant, calmative, cathartic, chloral hydrate,
   cleansing, codeine, codeine cough syrup, deadening, demulcent,
   depressant, depressor, dolly, dope, downer, drug, dulling, easing,
   emollient, goofball, hard stuff, heroin, hop, horse, hypnotic,
   junk, knockout drop, knockout drops, laudanum, lenitive, liquor,
   lotus, meperidine, methadone, mitigating, mitigative, morphia,
   morphine, narcotic, numbing, opiate, opium, pacifier, pain killer,
   pain-killer, pain-killing, palliative, paregoric, pen yan,
   phenacetin, phenobarbital, phenobarbital sodium, purgative,
   purple heart, quietener, quietening, rainbow, red, relieving,
   remedial, scag, secobarbital sodium, sedative, shit, sleep-inducer,
   sleep-inducing, sleeper, sleeping draught, sleeping pill, smack,
   sodium salicylate, sodium thiopental, softening, somnifacient,
   somniferous, soother, soothing, soothing syrup, soporific,
   stunning, stupefying, subduing, tar, tranquilizer, tranquilizing,
   turps, white stuff, yellow, yellow jacket