I have also heard of checks being called warrants. When I was a grad asst I went to finance to pick up my paycheck and was told the warrant could be picked up somewhere else on campus. I had to ask what the heck they meant! Hope yours is a big check or as the definition above indicates, a really cheap way to buy very high $ stocks ... maybe it will be Microsoft and issued back around 1980 (?) or so. Good luck.
Bekker