The process of locking up a girl for the cold winter months to hook up with while giving the girl a false impression of a potential serious relationship. The guy then lets her go when Memorial Day hits, the weather warms up and the sun dresses start coming out.

When you eat dirt for the first time and leave your family to build a shack in the woods

wintergirlfriend (noun) /wntr)gər(-ə)l-frend/ 1.women who allows you to have sexual relations with her from Halloween to Patties Day. 2.women in an urban area in which the temperature falls below 40 degrees a portion of the year that is used as a non verbal companion during Pro football and College basketball. 3.women to get you through winter until the first day other women start wearing sun dresses again.