Count: 0 — There are no authentic Irish girl names that start with J that meet the specified criteria. This list includes only female given names of clear Irish/Gaelic origin or long historical use in Ireland, with verified spellings, meanings, and pronunciations. Interesting detail: the letter J did not exist in traditional Irish orthography, so native Gaelic names rarely begin with that letter.

Understand why the search yields no results. Historic Irish orthography and phonology use letters and letter combinations different from English, so the /dʒ/ sound written with J in English is usually rendered by other letters in Gaelic. Authoritative sources (Ó Corráin, Foras na Gaeilge, Irish name registries and etymological dictionaries) show few or no historically attested Gaelic female names that start with J. Names beginning with J that are common in Ireland today — such as Jane, Joan, Julia, Josephine, Jade or Jasmine — are imports or later anglicisations, not original Irish-Gaelic names.

Consider close alternatives and practical options. If you want authentic Irish names with similar meanings or roles, choose names like Siobhán (shi-VAWN) for an Irish equivalent of Joan/Joanna, Sadhbh (SIVE) for a gentle, classical Irish female name, or Síle (SHEE-luh) as a traditional name often anglicised to Shelia/Sheila. Use these verified Gaelic names or accept that J names used in Ireland are typically English borrowings; consult Ó Corráin and Foras na Gaeilge for authoritative spellings, pronunciations, and historical attestation.