As a verb monest
is (obsolete) to warn; to admonish; to advise.
As an adjective gonest is
(gone).
gonest
English
Adjective
(head)
(gone)
References
* Google Books: [https://www.google.com/search?biw=1280&bih=881&tbm=bks&sclient=psy-ab&q=%22the+gonest%22&btnG=&oq=&gs_l=&pbx=1]