Shiksa is a Yiddish word that refers to a non-Jewish woman who is either romantically interested in a Jewish man or who is a Jewish man's object of affection. Although pop-culture has coined terms like "shiksa goddess," shiksa is not a term of endearment or empowerment. Because Jewish lineage is traditionally passed from mother to child, the possibility of a non-Jewish woman marrying into a Jewish family has long been seen as a threat. Any children she bore would not be considered Jewish, so that family's line would effectively end with her. However, in modern times the rising rate of intermarriage has caused some of the Jewish denominations to reconsider the ways in which lineage is determined. The Reform movement, for example, does allow a child's Jewish heritage to be passed down from the father.
The male equivalent of shiksa is "shaygets."
Examples: My son is heading off to college next year. Let's hope he dates a nice Jewish girl and doesn't fall for a shiksa!