Definition of j-school:
(n) :
(slang) A term for a marijuana cigarette ('joint').
(n) :
(mathematics) An alternative version of i, the positive square root of -1; used in the context of electronics.
(n) :
(mathematics) The second unit vector, after i
(n) :
(slang) (plural Js or J's) A marijuana cigarette (abbreviation of joint).
(n) :
(slang, chiefly in the plural) (plural Js or J's) an Air Jordan shoe
(n) :
In the name of a serial publication: abbreviation of Journal.