1540s, from supreme + -acy, or from Latin supremitatem (nominative supremitas). Supremity in same sense is from 1530s.
Entries linking to supremacy
supreme adj.
1520s, from French suprême (15c.) and directly from Latin supremus "highest," superlative of superus "situated above," from super "above" (from PIE root *uper "over"). Supreme Being "God" first attested 1690s; Supreme Court is from 1689.
-acy
word-forming element making nouns of quality, state, or condition, a confusion in English of three similar suffixes from Latin:
1. in primacy, etc., from Old French -acie and directly from Medieval Latin -acia, Late Latin -atia, making nouns of quality, state, or condition from nouns in -as.
2. in advocacy, etc., from Late Latin -atia, forming nouns of state from nouns in -atus.
3. in fallacy, etc., from Latin -acia, forming nouns of quality from adjectives in -ax (genitive -acis). Also forming part of -cracy. It has been extended in English to nouns not found in Latin (accuracy) and to non-Latin words (piracy).
supremacist n.
by 1948, originally with reference to racial beliefs and in most cases with white, from supremacy + -ist. Compare supremist. Related: Supremacism.