A romantic and/or sexual relationship in which the people involved are permitted or tolerated to be available to have additional simultaneous romantic and/or sexual relationships.

A chess opening in which white begins by playing 1.c4, moving his queen bishop's pawn to the fourth rank.

A configuration of a mouth wherein the front top teeth are separated vertically from the front bottom teeth even while the back top teeth are resting directly upon the back bottom teeth.

plural of open bite

Very startling or shocking; engaging a person's full attention.

(phonetics, of a vowel) pronounced with the tongue in a position approximately one-third of the way between an open and a close vowel

(hunting, sometimes followed by on or for to designate the kind of animal hunted) A period of time during the calendar year when authorities within a jurisdiction permit the unrestricted hunting of one or more kinds of animal wildlife.

plural of open marriage

A marital relationship in which each partner agrees that the other partner may have sexual relations with other people as he or she sees fit.

(rugby) the portion of the field which is larger as measured from a scrum or breakdown to the touchline