Also spelled schmeer and shmear. This is one of the many Yiddish words that has entered into the English language.
It may mean 'a bunch of stuff' (as in "I bought the whole schmear"), or 'a group of related things'.
It may also refer to flavored cream cheese used to top bagels. Schmear comes in a multitude of flavors, from various fruits to lox.
And finally, the definition most true to its etymology, it means 'a smear', or 'to smear'.