golden age

WordReference Random House Unabridged Dictionary of American English © 2025

gold′en age′, 

1. the most flourishing period in the history of a nation, literature, etc.
2. Mythology [Class. Myth.] the first and best of the four ages of humankind;
   an era of peace and innocence that finally yielded to the silver age.
3. Literature (usually caps.) a period in Latin literature, 70 b.c. to a.d. 14, in which Cicero, Catullus, Horace, Vergil, Ovid, and others wrote;
   the first phase of classical Latin. Cf. silver age (def. 2).
4. the period in life after middle age, traditionally characterized by wisdom, contentment, and useful leisure.
5. the age at which a person normally retires.
• 1545–55

Collins Concise English Dictionary © HarperCollins Publishers::

golden age noun

1. the first and best age of humankind, when existence was happy, prosperous, and innocent
2. the most flourishing and outstanding period, esp in the history of an art or nation: the golden age of poetry