Webster's Revised Unabridged Dictionary · 1913

to wrap and seal (an object for sale) in a transparent sheet of plastic material that is shrunken to a tight-fitting wrapping by the application of heat.

a type of plastic film, usually transparent, that shrinks upon application of heat, and may be used to form a wrapping around objects that fits tightly and closely follows the contours of the wrapped object; -- also called shrink-pack, shrinkpack or shrink-wrapping.