J has 5 different meanings across 2 categories:
Noun · Character
a unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second
the 10th letter of the Roman alphabet
A term for a marijuana cigarette ('joint').
(plural Js or J's) A marijuana cigarette. (Abbreviation of joint.)
The tenth letter of the English alphabet, called jay and written in the Latin script.