UN-

(prefix denying presence or possession of thing or quality) ú- (no-, not, un-, in-) (according to LR:396 s.v. UGU, this prefix usually has a "bad sense", cf. vanimor "fair folk" vs. úvanimor "monsters"), il- (denoting "the opposite, the reversal, i.e., more than the mere negation"), also pretonic prefix la- "un-, not-". –VT39:14, UGU, UMU, LT1:255, VT45:25