Latin legal term, "on the one side only," from ex "out of" (see ex-) + parte, ablative of pars "a part, piece, a division, a fraction, a side of the body" (from PIE root *pere- (2) "to grant, allot").
ex-
ex cathedra
ex libris
ex nihilo
ex officio
ex parte
ex post facto
exacerbate
exacerbation
exact
exacta