'ascendency' originates from Latin, specifically the word 'ascendere', where 'ad-' (often assimilated to 'as-') meant 'toward' and 'scandere' meant 'to climb'.

'ascendency' developed through Late Latin and Old French/Medieval English forms such as 'ascendence'/'ascendancy' and later stabilized as the modern English 'ascendency' (a variant of 'ascendancy').

Initially it referred to the act of rising or climbing; over time it evolved to mean a figurative rising — a holding of dominant influence or control.