ad·mon·ish / ədˈmänish/ • v. [tr.] warn or reprimand someone firmly: she admonished me for appearing at breakfast unshaven. ∎  advise or urge (someone) earnestly: she admonished him to drink no more than one glass of wine. ∎ archaic warn (someone) of something to be avoided: he admonished the people against the evil of such practices.DERIVATIVES: ad·mon·ish·ment n.

admonish XIV. ME. amonesten — OF. amonester — Rom. *admonestāre, unexpl. deriv. of L. admonēre, f. AD- + monēre advise (cf. MONITION). The initial syll. was latinized to ad-, and the final syll. became -ish by assoc. with -ISH2.
So admonishment XIII (first a(d)monestement). admonition XIV (first amonicio(u)n).