A recent question on ELU made me realize that the idea of “Third Age” as defined below is used mainly in BrE and other European languages, while AmE speakers appear to be unfamiliar with it.
the period of time that is after middle age and before old age, when people are still active. (MacMillan Dictionary)
Form the extract below it appears that the idea started in France but was actually carried out on a larger scale in England:
an international organization aimed at providing 'lifelong learning for older people'. It organizes courses and other activities for retired people. It started as part of a university in France in 1973 and the first U3A group started in the UK in 1983 after the creation of a charity The Third Age Trust. Most courses in the UK are taught by U3A members themselves using their knowledge and experience. (OLD)
Where did the expression originate? Is it originally BrE or does it come from other European languages? What’s the AmE equivalent expression for “third age”?