The story
From pre- (prefix meaning ‘before; physically in front of’) + Latin fōrmāns (“fashioning, forming, shaping”) + -ant (suffix forming agent nouns from verbs), modelled after prefix. Fōrmāns is the present participle of fōrmō (“to fashion, form, format, shape”), from fōrma (“appearance, figure, form, shape; beauty; design, outline, plan; model, mould, pattern, stamp; (figuratively) kind, manner, sort”) (further etymology uncertain) + -ō (suffix forming first-conjugation verbs).
Etymology from Wiktionary, CC BY-SA 4.0.