A jock is a young man who is enthusiastic about a particular sport and spends a lot of time playing it. Some people use this term to suggest that the person has few other interests and is not very clever.
[informal]
...an all-American football jock.
2. countable noun
A jock is the same as a disc jockey.
[informal]
...the foolish radio jock who had dismissed the album.
jock in British English
(dʒɒk)
noun
1. informal short for disc jockey
2. informal short for jockstrap
3. US informal
an athlete
4. New Zealand mining
a pointed bar of steel inserted into the wheel of a mine vehicle and used for emergency braking