ascendancy

Short definition from Wiktionary

Noun

1. 1
   The quality of being in the ascendant; dominant control, supremacy.
2. 2
   Ellipsis of Protestant Ascendancy, a class of Protestant landowners and professionals that dominated political and social life in Ireland up to the early 20th century.
3. 3
   A quantitative attribute of an ecosystem, defined as a function of the ecosystem's trophic network, and intended to indicate its ability to prevail against disturbance by virtue of its combined organization and size.