junta, jelly, joust
A four letter word starting with J is jump or joke.
joust
jamoke
Some 5-letter words beginning with 'j' are:jabotjauntjazzyjeansjellyjennyjettyjeweljiffyjimmyjointjoistjokerjollyjoulejoustjowlyjudgejuicejuicyjulepjumbojumpyjunkyjuror
Fuji
JunkJambJustJoinJail
java
Some five letter words that start with J are:jauntjawedjellyjeweljimmyjointjokerjoustjudgejuror
Judge.
Reenact. -J
Possibly 'jurisdiction.'
jumpy, jealous