| Term | Definition |
| jaded | dulled by overindulgence; fatigued |
| jargon | language used by special group |
| jaundiced | prejudiced; envious |
| jaunty | stylish; perky; carefree |
| jingoism | aggressive militant patriotism |
| jocular | said or done in jest |
| judicious | sound in judgement; wise |
| juggernaut | irresistible crushing force |
| juxtapose | place side by side |
| kindle | start a fire; inspire |
| kindred | belonging to the same family |
| kleptomaniac | one who has a compulsive desire to steal |
| lackadaisical | lacking spirit or zest; lazy |
| lackluster | dull |
| laconic | brief and to the point |
| laggard | slow; sluggish |