What does this word mean?
It’s not in any of my dictionaries, but there are a few too many occurrences of this word in programming communities and across the Internet for me to believe that these people all really mean “instantiate.”
Bonus: Argue for a correct spelling.
in·stan·ti·ate | \in-ˈstan(t)-shē-ˌāt
: to represent (an abstraction) by a concrete instance
heroes instantiate ideals
After reading more than a handful of the Stack Overflow posts that you linked in your question, I can confidently say that they are all misspelling instantiate.