- j ... Jacaranda cuspidifolia
- Jacaranda mimosifolia ... Jackson, Bo
- Jackson, Busher ... Jacmel
- Jaco ... Jacopone da Todi
- Jacotot, Jean-Joseph ... jaggery
- Jaghbūb, Al- ... Jakob von Gunten
- Jakob, Alfons M. ... Jamanota, Mount
- Jamasp ... James, Preston E.
- James, Rick ... Jan Six
- Jan van Avesnes ... jansky
- Jansky, Karl ... Japanese box
- Japanese boxwood ... Japelli, Giuseppe
- Japheth ... Jashar, Book of
- Jashore ... Java Runtime Environment
- Java Sea ... Jayaram, Jayalalithaa
- Jayasena, Henry ... Jean le Bon
- Jean le Conquérant ... Jeffersonian Republicans
- Jeffersons, The ... Jena glass
- Jena Romanticism ... Jephtha
- Jephthah ... Jerusalem, Hebrew University of
- Jerusalem, kingdom of ... jeté
- jeté battu ... Jewish fundamentalism
- Jewish Historical Museum ... Jiang Jie-shi
- Jiang Jieshi ... jiguan
- Jih-k’a-tse ... Jing River
- Jing-Hang Yunhe ... Jiuguo
- Jiuhua Mountains ... Joan I
- Joan II ... jōe
- Joe ... John
- John ... John II
- John II ... John the Divine, Saint
- John the Elder ... Johnny Panic and the Bible of Dreams
- Johnny Stecchino ... Johnson, J. J.
- Johnson, Jack ... Johnston, Harriet Lane
- Johnston, Henrietta ... Jokić, Nikola
- Jokin ... Jones, Absalom
- Jones, Alex ... Jones, Michael
- Jones, Mick ... Jordan algebra
- Jordan curve theorem ... Joseph
- Joseph and His Brethren: A Scriptural Drama in Two Acts ... Josue
- Josue, Book of ... Journey for Margaret
- Journey from St. Petersburg to Moscow, A ... JPMorgan Chase & Co.
- JPod ... Jubilee, Year of
- Jubilees, Book of ... Judge, William Q.
- judgement ... Juggler of Notre Dame, The
- Juglandaceae ... Julian the Apostate
- Julian, Académie ... Jumhūriyyah al-Lībiyyah, Al-
- Jumhūriyyah al-Lubnāniyyah, Al- ... Jung, Andrea
- Jung, Carl ... Juno
- juno ... jus cogens
- jus commune ... Justification of God, The
- Justified ... Jyväskylä