Well, there's jewelry. Also jealous.
Fuji
Reenact. -J
jumpy, jealous
juniper, jumping, joshing, jarring, jesting
A seven letter word that can be made from those letters is franker (comparative form of the adjective 'frank').
A four letter word starting with J is jump or joke.
joust
jamoke
Fuji
JunkJambJustJoinJail
java
Reenact. -J
junta, jelly, joust
Possibly 'jurisdiction.'
jumpy, jealous
joyful
i dont know the answer either!