Princeton's WordNet

1. Union Jack, Union flag(noun)

   national flag of the United Kingdom

Wiktionary

1. Union Jack(Noun)

   The flag of the United Kingdom, consisting of the flags of England (St. George's Cross), Scotland (St. Andrew's Cross), and Ireland (St. Patrick's Cross) now only used in Northern Ireland combined.

2. Union Jack(Noun)

   The flag, consisting of the blue star-studded field in the corner of the national ensign, flown at the jack staff by ships at anchor.

3. Union Jack(Noun)

   The flag, consisting of the flags of England, Scotland, and Northern Ireland combined, flown on ships of the government of the United Kingdom

The Nuttall Encyclopedia

1. Union Jack

   originally the flag of Great Britain, on which the crosses of St. George and St. Andrew are blended, with which certain white streaks were blended or fimbriated after the Union with Ireland.

• Union JackAfrikaans
• العَلَم البريطانيArabic
• националното знаме на Обединеното кралствоBulgarian
• bandeira inglesaPortuguese (BR)
• britská státní vlajkaCzech
• der Union JackGerman
• Union JackDanish
• η βρετανική σημαίαGreek
• bandera del Reino UnidoSpanish
• Suurbritannia riigilippEstonian
• پرچمFarsi
• Ison-Britannian lippuFinnish
• Union JackFrench
• הַדֶגֶל הַבּרִיטִיHebrew
• यूनियन जैकHindi
• zastava Velike BritanijeCroatian
• a brit zászlóHungarian
• bendera InggrisIndonesian
• breski ríkisfáninnIcelandic
• (bandiera nazionale britannica)Italian
• 英国国旗Japanese
• 영국 국기, 유니언 잭Korean
• Britanijos nacionalinė vėliavaLithuanian
• Lielbritānijas valsts karogsLatvian
• bendera Union JackMalay
• Britse vlagDutch
• det britiske nasjonalflaggetNorwegian
• flaga brytyjskaPolish
• bandeira inglesaPortuguese
• Union Jack, steagul Marii BritaniiRomanian
• государственный флаг ВеликобританииRussian
• štátna vlajka Veľkej BritánieSlovak
• državna zastava Velike BritanijeSlovenian
• zastava Ujedinjenog KraljevstvaSerbian
• Union JackSwedish
• ธงชาติของอังกฤษThai
• Birleşik Krallık BayrağıTurkish
• 英國國旗Chinese (Trad.)
• державний прапор Великої БританіїUkrainian
• برطانيہ کا قومي پرچمUrdu
• quốc kì AnhVietnamese
• 英国国旗Chinese (Simp.)