An opening made in the wall of a house to admit light and air, and to enable those who are in to look out. 2. The owner has a right to make as many windows in his house when not built on the line of his property as he may deem proper, although by so doing be may destroy the privacy of his neighbors. 3. In cities and towns it is evident that the owner of a house cannot open windows in the partition wall without the consent of the owner of the adjoining property, unless he possesses the right of having ancient lights. The opening of such windows and destroying the privacy of the adjoining property, is not, however, actionable; the remedy against such encroachment is by obstructing them, without encroaching upon the rights of the party who opened them, so as to prevent a right from being acquired by twenty years use.
WINDOW
TheLaw.com Law Dictionary & Black's Law Dictionary 2nd Ed.