Webster's Revised Unabridged Dictionary · 1913

Separatist

Separatist , noun

[Compare French séparatiste.]

One who withdraws or separates himself; especially, one who withdraws from a church to which he has belonged; a seceder from an established church; a dissenter; a nonconformist; a schismatic; a sectary.
Heavy fines on divines who should preach in any meeting of separatist. — Macaulay