Genealogy /
SKI...SKY...ZKI...Polish surname endings [38]
it's an adjectival suffix that mostly denotes area or place of origin of something (or showing some other connection with the place area) - it can be translated as 'of a place'
Kraków - krakowski = (of Kraków)
Kowalewo - kowalewski - (of Kowalewo)
Kowale - Kowalski - (of Kowale)
Warszawa - warszawski - (of Warszawa)
however -ski (-ska, -skie) adjectives can be created not only of place names - with a meaning of '-like' it is added to various nouns and you've got - przyjacielski (friendly), męski (manly or gents'), żeński (feminine), ludzki (human or humane)
in even broader class of man related names (like names of professions) -ski means belonging to the profession/art - młot kowalski - blacksmith's hammer, zestaw malarski - painting (painter's) set, kadź barwierska - dyer's vat, pieśń żołnierska - soldierly (soldiers') song,
the suffix has a quite defined history in Slavic languages (all Slavic languages share it) - and it is cognate (the developement of the same origin) to English -ish, -sh suffix (as in Polish, English, Welsh) - in English it developed from -isk, -sk suffix which is still present in Scandinavian languages (in Danish you;ve got Dansk=Danish, Engelsk=English, Norsk=Norwegian, Swensk=Swedish, Polsk=Polish, Tysk=German (Deutsch), Jysk= Jutlandish (of Jutland), Rysk = Russian
the most probable occurence is that -sk suffix originated in Germanic languages suffix originally used for nations and lands and was borrowed from Germanic Gothic language into Slavic when the two languages were in contact in late antiquity to very early middle ages (sharing the fate of many other borrowings from Gothic to Slavic which are still present in most Slavic languages)