I can't seem to find the search button. Also, can someone define what "side effects" are, please. I am studying Scheme now and I don't understand the relevance of "side effects" to Scheme or anything else.
Something done by code that isn't represented by the return value of that code. For instance, if you define a function that changes a global variable and then returns double its argument, the change to the global variable is a "side effect". See also "pure functional" (code which doesn't have side effects).
That's not the kind of definition this dictionary is going for, though; that's tech jargon, not startup jargon.