1. A "twist-tie", "twisttie" "twistie" pronounced either "twist tee" ,or "twist tie" is a short version of the words "twist tie", which is a piece of wire wrapped in paper (back in the good ole days) or on plastic. It is used after you twist a loaf of bread in the plastic wrapper - the twisttie is bent around the part where you spun the bread bag and where the bag is all twisted together in a tight "twist". Twistties (plural of twisttie) come in many colors, lengths, and widths.
2. Another fun use for this word, and it's derivatives is to use them in tongue twisters (pun intended). Hehehehe!
1. He took the twisttie and tied up the bread bag with it so that it wouldn't come undone; this kept the bread fresh for us.