- J ... Jacaranda cuspidifolia
- Jacaranda mimosifolia ... Jackson, Bo
- Jackson, Busher ... Jacksonville Jaguars
- Jacksonville University ... Jacopo di Cione
- Jacopo Strada ... Jagger, Bianca
- Jagger, Dean ... Jakarta Zoological Gardens
- jake ... Jamāl-zādeh, Muhammad ʿAli
- Jamalpur ... James, Jesse Woodson
- James, Jesse; and James, Frank ... Jan Kazimierz Waza
- Jan Lokpal Bill ... Jansch, Bert
- Jansch, Herbert ... Japanese anemone
- Japanese aralia ... Japanese varnish tree
- Japanese War Bride ... Jarves, Deming
- Jarvi, Neeme ... Jaurès, Jean
- Jauru River ... Jaya Peak
- Jaya Sthiti ... Jean de Matha
- Jean de Méricour ... Jefferson Seminary
- Jefferson Starship ... Jemisin, N. K.
- Jemisin, Nora Keita ... Jensen, Johannes Hans Daniel
- Jensen, Johannes Hans Daniel ... Jerusalem Bible
- Jerusalem Conference ... Jet
- jet ... Jewish Agricultural Society
- Jewish Autonomous Region ... jia
- Jia Sidao ... jig-rtenskyong
- jigai ... Jin Shizu
- Jin Yong ... Jippensha Ikku
- jiqiu ... Joachim, Harold Henry
- Joachim, Harry ... Joconde, La
- jocs florals ... Johannis
- Johannisberg riesling ... John Hyrcanus II
- John I ... John of Scythopolis
- John of Struma ... John, Sir Elton Hercules
- John, Tommy ... Johnson, Eliza
- Johnson, Ellen ... Johnson, Tommy
- Johnson, Uwe ... jointed charlock
- jointing plane ... Jonas of Orléans
- Jonas, Book of ... Jones, Jesse H.
- Jones, Jesse Holman ... jonna
- Jonny Spielt Auf! ... Jory, Victor
- Jos ... Joshua Tree National Monument
- Joshua Tree National Park ... Journal of Madame Knight, The
- Journal of My Life, The ... Joyce, James Augustine Aloysius
- Joyce, Mike ... juba
- Juba ... Jude, St.
- Judea ... jūdōgi
- Judson Dance Theater ... Jules Verne Trophy
- Juli, El ... July
- July 20 Museum ... junction effect
- junction field-effect transistor ... Junior Bonner
- junior college ... Jurchen language
- Jürchid dynasty ... Juster, Norton
- Justice ... juvenile court
- juvenile delinquency ... Jyväskylä