Plural of brilliancy: multiple instances of great brightness, brilliance, or outstanding excellence.
From 'brilliancy' plus the plural suffix '-ies.' Brilliancy itself comes from 'brilliant,' ultimately from Latin 'berillus' (beryl, a shining gemstone).
The word 'brilliancy' is one of those Victorian-era terms for excellence that sounds almost quaintly formal today—it captured the 19th-century obsession with describing moral and intellectual qualities through the metaphor of light.
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