| Name | Meaning | Gender | Origin |
|---|
| Jo | Variation of Johanna, God is gracious | Female | English |
| Joey | Abbreviation of Joseph.
| Male | |
| Joey | Abbreviation of Joseph.
| Male | |
| Jordan | The descending river, to flow | Male | Hebrew |
| Joyce | after James Augustine Aloysius Joyce, Irish writer and poet | Female | Latin |
| Jules | youthful; soft, downy | Male | |
| Justice | Just, Fairness | Female | English |
| Kai | Fire
| Male | Hawaiian |
| Keegan | A thinker: fiery. Form of Hugh.
| Male | Irish |
| Kel | | Unisex | Hebrew |
| Kelly | Lively: aggressive.
| Female | Irish |
| Kelsey | Ceol's island, beautiful island; from the ship's island, shipping harbor | Female | English |
| Kendall | ruler of the valley | Female | English |
| Kennedy | misshapen head | Female | Irish |
| Kim | chief | Male | English |
| Kimberly | Cyneburga's Royal Forest, Meadow | Female | English |
| Kit | Nickname for Christopher. Frontiersman Kit Carson.
| Male | English |
| Kyle | A place-name referring to the narrows: a wood or a church.
| Male | Scottish |
| Lane | narrow road | Male | English |
| Lee | Healer
| Male | English |
| Leigh | meadow | Female | English |
| Leslie | dweller in the gray castle; small meadow | Female | Scottish |
| Lindsay | pool island; linden island | Female | English |
| Logan | little hollow | Male | Scottish |
| London | fierce ruler of the world | Female | English |