prime
n. uncountablen. the period in your life when you are most successful, active, or strong.
n. the period of greatest strength, vigour, or success in a person's life or a thing's existence.
The athlete is currently in the prime of his career.
Many people believe that they reach their intellectual prime during their thirties or early forties.
The historic building was restored to its former glory, reflecting the architectural grandeur it possessed during its Victorian prime.
From Middle English prime, from Old French prime and its etymon, Latin prīmus (“first”), from earlier prīsmos < prīsemos < Proto-Italic priisemos, ultimately from Proto-Indo-European *per- (“beyond, before”). Doublet of primo and primus. The noun sense "apostrophe-like symbol" originates from the fact that the symbol ′ was originally a superscript Roman numeral one.
Related to primage and Latin prīmus.
From French prime (“reward, prize, bonus”).
Usually occurs in the singular form and is frequently preceded by the definite article and followed by a prepositional phrase starting with 'of'.