jove
Synonym discussion
Sense: noun/1
All four expressions react to surprise or add emphasis, but they fit different speakers and times. 'By Jove' is the most old-fashioned of the group, strongly British, and now mostly heard from older speakers or in books set before the Second World War; using it today can sound jokey or theatrical, as if the speaker is imitating a stage colonel. 'Goodness' is the safe, modern, neutral British choice and works in any company. 'Blimey' is also British and informal but younger and more working-class in feel — closer to a market-stall reaction than a club armchair. 'Wow' is the broadest of the four: shared across English-speaking countries, fine in writing, and at home in both small talk and excited reaction. For example, a learner today should pick 'wow' or 'goodness' over 'by Jove' unless the goal is a clear period or comic effect.
Etymology
From the Latin name 'Iovis', a form of 'Jupiter', the chief god of the Roman pantheon. In English the form 'Jove' has been used since the 14th century as a poetic name for Jupiter, and from the 16th century the oath 'by Jove' replaced 'by God' as a milder way to swear without breaking the religious taboo on God's name.