JL (Judkins left (catheter))

JME (juvenile myoclonic epilepsy)

JMML (juvenile myelomonocytic leukemia)

JNCL (juvenile neuronal ceroid lipofuscinosis)

JND (just noticeable difference)

jnt (joint)

JOD (juvenile-onset diabetes)

JODM (juvenile onset diabetes mellitus)

JP (Jackson-Pratt (drain))

JPS (juvenile polyposis syndrome)