"not conformable to the rules or principles of art" [Century Dictionary], 1836, from in- (1) "not" + artistic. Inartistical is attested from 1849. Related: Inartistically.
inapprehensible
inappropriate
inapt
inaptitude
inarticulate
inartistic
inasmuch
inattention
inattentive
inaudibility
inaudible