The best tool for finding words that begin with any particular letter is a hard-copy dictionary, which lists words in alphabetical order.
For a somewhat shorter list without definitions, try one of the many "spelling dictionaries" available.
Words that start with J include:
jab
jabber
jack
jack-o-lantern
jackal
jacket
jackknife
jackpot
jade
jail
jam
janitor
jar
jaw
jazz
jealous
jeans
jeer
jerk
jest
jester
jet
jewel
jewelry
jib
jiffy
jingle
jock
joey (baby kangaroo)
jog
join
joint
joke
joyful
joyous
judge
jug
jump
jumper
junction
juncture
jungle
juniper
junk
juror
jury
just
justice
Jupiter
Jack-in-the-box (toy) Jack-o-lantern
Jacket
jalapeno
jacuzzi
jellyfish
Jewels Jar Joe Jump Jesus Jerusalem Jade Joy Jelly Jam Jewelry Jock Jail
Junk Jerk Japanese Japan
Java Joke Jaguar Job Jennifer John Jimmy Neutron Jupiter Jolly Jessica Jesse Jim Carey Jillian Juno (the movie) jockey Jack Nicholson
Jacks (the game) Jack (for the car) Jeans
Jet Airplane
jet engine
jello
jelly bean
jigsaw puzzle
jingle bells
joystick
jump rope
jumpers (clothing)
jungle gym (found in playgrounds)
Jives
Joint
Juice
Jaw
Jewels
Jackpot
jackknife
jaguar
jail
jazz band
junkyard
junk food
jugs
jade (color)
By the one and only Cuddles aka Chio
15 words that start with letter J are:jadejaguarjamboreejavajealousjerseyjesterjinglejivejobjokejollyjudgejuryjust
There are hundreds of words that start with the letter j. There are less than 6 words that end with the letter q. There are no words that start with j and end with q.
Some words that start with M and include a letter J are:majestymajormajorityMojave Desertmojo
Thousands of English words start with the letter b. Less than ten English words end with the letter j. No Scrabble words start with b and end with j.
Thousands of words start with the letter e. Less than ten words end with the letter j. No Scrabble words begin with e and end with j.
Some five letter words that start with J are:jauntjawedjellyjeweljimmyjointjokerjoustjudgejuror
j
Just and judicious are complimentary words. They begin with the letter j.
There are hundreds of words that start with the letter j. There are less than 10 words in the English language that end with the letter j. There are no words that begin and end with the letter j.
Jesuits
Five letter words starting with J and ending in E:judge
Some four letter words that start with J are:jokeJunejustjuryjailJoveJerkjumpjestjeerjunkjive