Does -wich suffix (as in Greenwich, sandwich, etc.) have a meaning?
According to Wikipedia, -wich derives from an Anglo-Saxon suffix meaning roughly "a dwelling or fortified place" with extensive trading activity, usually on a coast.
It is ultimately of Latin origin, where the meaning can be more varied and vague: dwelling, dwelling-place; village, hamlet, town; street in a town; farm, esp. a dairy-farm.
The suffix -wich is leftover from the Anglo-Saxon language. It meant farm and only exists now in place names such as Greenwich, Ipswich, Norwich, etc.
Other such Anglo-Saxon hold overs used in place names are -ham (village), -leigh/-lee/-lea (forest clearing), -dun (lake), and -bury (fortified place). They are not used in modern language, they have simply survived since the Anglo-Saxons named them.