"lord of a manor," late 13c., from Old French seignior (11c., Modern French seigneur), from Latin seniorem (nominative senior) "older" (from PIE root *sen- "old"). As a general title for a Frenchman, it dates from 1580s. Related: Seigniorial; seignioral.
segregation
segregationist
segue
Segway
seigneur
seignior
seigniorage
seine
seisin
seismic
seismo-