Dictionary.net

mug-l-t[=o]'ni-an, n. a member of a sect founded in England by John Reeve and Lodowick Muggleton (1607-97), which lingered till well into the 19th cent. They claimed to be the two witnesses of Rev. xi. 3-6, denied the Trinity, holding grotesque anthropomorphist opinions, with many strange doctrines over and above, as that the devil became incarnate in Eve, &c.

(Member) of sect founded by, & believing in personal inspiration of, Latin Muggleton& John Reeve, c. 1650.