A four letter word starting with J is jump or joke.
Some four letter words that start with J are:jokeJunejustjuryjailJoveJerkjumpjestjeerjunkjive
There are no 4 letter words in the English language that begin with the letter L and end with the letter J.
ajar, ajax
jade
jack
Jack, Jade, Jaws!
June
Jolt, Jamb
jest, jape, joke
jerk, jail
jerusalem