An Etymological Dictionary of the German Language/Annotated/gätlich
gätlich, adjective, ‘suitable, convenient,’ an essentially Middle German and Low German word; derived from a parallel Gothic form *gada-, to which Old High German gi-gát, adjective, ‘suitable, agreeing with,’ also points; compare Gatte, gut; so too Old Slovenian godŭ, ‘favourable time,’ Lithuanian gadas, ‘stipulation,’ and Dutch gadelijk, ‘reconcilable.’