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Words that start with the letter J

J words are less common than many other letters, which makes them fun for word games and useful for spelling practice. This list mixes simple, kid-friendly words with a handful of science and math terms that begin with J.

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Words that start with the letter J

32 words
WordMeaningIn a sentenceSave
jacketnounA short coat, usually reaching the hips, worn over other clothing for warmth or style.He grabbed a light jacket before heading out into the cool evening air.
jaguarnounA large, powerfully built wild cat with a spotted coat, native to Central and South America.The jaguar moved silently through the rainforest, tracking a wild pig.
jarnounA cylindrical container, typically made of glass, used to store food or other substances.She sealed the homemade jam in a glass jar before storing it in the pantry.
jawnounEither of the two bony structures that form the mouth and hold the teeth.He clenched his jaw in frustration but said nothing during the meeting.
jazznounA style of music, originating among African Americans, known for improvisation and syncopated rhythms.The band played smooth jazz late into the night at the small club.
jealousadjectiveFeeling resentful envy of someone's achievements, possessions, or advantages, or fearful of losing someone's affection to a rival.He felt jealous when his friend got the promotion he had been hoping for.
jellynounA soft, semi-solid food made by setting fruit juice or another liquid with gelatin or pectin.She spread jelly on her toast alongside a thick layer of peanut butter.
jesternounA person, historically employed by royalty, who entertained the court with jokes, music, and tricks.The court jester juggled and told riddles to amuse the king's guests.
jewelnounA precious stone, especially one cut and polished for use in jewelry.A single ruby jewel was set at the center of the antique ring.
jigsawnounA puzzle made of many irregularly shaped pieces that interlock to form a complete picture.They spent the rainy afternoon assembling a thousand-piece jigsaw of a mountain landscape.
jobnounA paid position of regular employment, or a specific piece of work that needs to be done.She landed her first job as a graphic designer right out of college.
jogverbTo run at a slow, steady pace, typically for exercise or fitness.He jogs around the park every morning before going to work.
joinverbTo connect or link with something else, or to become a member of a group or activity.Please join us for a quiet dinner this Saturday evening at seven.
jointnounA point where two or more bones, parts, or structures connect and often move.Cold weather often makes the pain in her knee joint worse.
jokenounSomething said or done to cause amusement or laughter, such as a short funny story.He told a joke that made the whole classroom burst out laughing.
journalnounA daily written record of events and thoughts, or a periodical publication on a specific subject.She writes in her journal every night before going to sleep.
journeynounAn act of traveling from one place to another, especially over some distance.The journey to the island included a train ride and a short ferry crossing.
joynounA feeling of great happiness and delight.The children's laughter filled the house with joy on Christmas morning.
joyfuladjectiveFull of great happiness, or causing others to feel delighted.The wedding was a joyful celebration filled with music and laughter.
judgenounA public official with the authority to hear and decide cases in a court of law.The judge listened carefully before delivering her decision on the case.
juggleverbTo keep several objects moving through the air by tossing and catching them skillfully.The street performer juggled five flaming torches without dropping a single one.
juicenounThe natural liquid contained in fruit, vegetables, or other substances.She squeezed fresh orange juice for breakfast almost every single morning.
jumpverbTo push off the ground using the legs and spring suddenly into the air.The children loved to jump over the puddles after the rain.
jumboadjectiveVery large in size, especially compared to others of the same kind.The airline flies a jumbo jet capable of carrying hundreds of passengers.
junglenounA dense tropical forest with thick vegetation and abundant, often exotic, wildlife.Explorers hacked their way through the jungle in search of the ancient ruins.
junioradjectiveLower in rank, age, or experience compared to others in the same field.She started as a junior analyst before being promoted to team leader.
jurynounA group of citizens sworn to hear evidence and reach a verdict in a legal case.The jury deliberated for two days before reaching a unanimous verdict.
justadverbVery recently, only, or exactly, used to emphasize a small amount, limit, or precision.We just arrived, so we haven't seen the rest of the house yet.
justicenounFair treatment of people according to the law or according to what is morally right.The victims' families waited years for justice after the long legal battle.
juvenileadjectiveRelating to, intended for, or characteristic of young people who are not yet adults.The library has a large juvenile section filled with books for young readers.
joulenounThe SI unit of energy or work, equal to the force of one newton acting over one meter.The physics problem asked students to calculate energy in joules, not calories.
jetnounAn aircraft powered by jet engines, or a fast, forceful stream of liquid or gas.The military jet roared low over the airfield before climbing sharply.

Science words that start with J

Science vocabulary beginning with J is limited, but a few useful terms exist. A joule is the standard unit of energy, a joint is where two bones meet in anatomy, and juvenile describes a young animal or an early life stage. The jet stream, a fast-moving band of air high in the atmosphere, is another common example from earth science.

Math vocabulary words that start with J

J is one of the rarest starting letters in math vocabulary, and most school-level math glossaries do not include a dedicated J term. Students searching for one often land on joint, as in joint variation, where one quantity depends on two or more others at once. Beyond that, J words show up far more in science and everyday language than in basic math.

Frequently asked questions

Are there any math words that start with J?

Very few. Joint variation, where a quantity depends on two or more other quantities, is one of the only common examples.

What are some J words for kids?

Simple, kid-friendly examples include jacket, jelly, jump, jungle, and joy.