Derived from the word Amyl, Omil is a term used by some drug users for Poppers or Amyl Nitrate. Refers to a small, usually brown bottle of solvents, which is sniffed to bolster the hallucinogenic effects of another drug already consumed, such as LSD, Extacy or a perhaps with Pot after a Pipe or Bong. Mainly inhaled through the mouth to give a higher dosage.
"Pass me that bottle of Omil, I'm going for the complete head fuck this time."
"My lips and nostrils are red raw with yellow scabs, I think I better lay off the Omil."