The noun ascendancy means a position of power, strength, or domination.

Synonyms are authority, dominance, influence, or reign.

The word origins in 1712. It is derived from ascendant plus –cy meaning “dominant power or influence, state of being in the ascendant”.

They are in menace of losing their political ascendancy.

Winter is swiftly in full ascendancy.

Their contestant is currently in ascendancy over their opponents.