[n] an advocate of secession or separation from a larger group (such as an established church or a national union)
[adj] having separated or advocating separation from another entity or policy or attitude; "a breakaway faction"
\Sep`a*ra*tist\, n. [Cf. F. s['e]paratiste.] 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.