n 1  :  a preparation (as morphine, heroin, and codeine) containing or derived from opium and tending to induce sleep and to alleviate pain  2  :  a synthetic drug capable of producing or sustaining addiction similar to that characteristic of morphine and cocaine  :  a narcotic or opioid peptide - used esp. in modern law
adj 1  :  of, relating to, or being opium or an opium derivative  2  :  of, relating to, binding, or being an opiate < receptors>  .
 
   
 
Similar sounding terms:  OPD  opi·oid  opt 
 
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