2. the number one: "the slope of each dotted line is less than unity"
3. in Aristotle's Poetics, each of the three dramatic principles requiring limitation of the supposed time of a drama to that occupied in acting it or to a single day (unity of time), use of one scene throughout (unity of place), and concentration on the development of a single plot (unity of action).
Word OriginMiddle English: from Old French unite, from Latin unitas, from unus ‘one’.