Definition of reefers:
(n) :
(countable) A marijuana cigarette.
(n) :
(uncountable) Marijuana.
(n) :
(colloquial, chiefly US) A refrigerated, insulated trailer, ship or shipping container.
(n) :
(rail transport, US) a refrigerator car (type of boxcar).
(n) :
A reefer jacket; a close-fitting jacket or short coat of thick cloth.
(n) :
(nautical) Someone who reefs sails, especially a midshipman.