WordNet (r) 3.0 (2006):

blue devil
    n 1: a coarse prickly European weed with spikes of blue flowers;
         naturalized in United States [syn: blueweed, blue
         devil, blue thistle, viper's bugloss, Echium
         vulgare]
    2: the sodium salt of amobarbital that is used as a barbiturate;
       used as a sedative and a hypnotic [syn: amobarbital sodium,
       blue, blue angel, blue devil, Amytal]

Moby Thesaurus II by Grady Ward, 1.0:

83 Moby Thesaurus words for "blue devil":
   Amytal, Amytal pill, Demerol, Dolophine, H, Luminal, Luminal pill,
   M, Mickey Finn, Nembutal, Nembutal pill, Seconal, Seconal pill,
   Tuinal, Tuinal pill, alcohol, amobarbital sodium, analgesic,
   anodyne, barb, barbiturate, barbiturate pill, black stuff, blue,
   blue angel, blue heaven, blue velvet, calmative, chloral hydrate,
   codeine, codeine cough syrup, depressant, depressor, dolly, downer,
   goofball, hard stuff, heroin, hop, horse, hypnotic, junk,
   knockout drops, laudanum, liquor, lotus, meperidine, methadone,
   morphia, morphine, narcotic, opiate, opium, pacifier, pain killer,
   paregoric, pen yan, phenobarbital, phenobarbital sodium,
   purple heart, quietener, rainbow, red, scag, secobarbital sodium,
   sedative, shit, sleep-inducer, sleeper, sleeping draught,
   sleeping pill, smack, sodium thiopental, somnifacient, soother,
   soothing syrup, soporific, tar, tranquilizer, turps, white stuff,
   yellow, yellow jacket