Merriam-Webster Collegiate Dictionary - proportion

 I. noun  Etymology: Middle English proporcion, from Anglo-French, from Latin ~-, proportio, from pro for + portion-, portio portion — more at for  Date: 14th century  1. harmonious relation of parts to each other or to the whole ; balance, symmetry  2.  a. proper or equal share each did her ~ of the work  b. quota, percentage  3. the relation of one part to another or to the whole with respect to magnitude, quantity, or degree ; ratio  4. size, dimension  5. a statement of equality between two ratios in which the first of the four terms divided by the second equals the third divided by the fourth (as in 4/2=10/5) — compare extreme 1b, mean 1c  II. transitive verb  (~ed; ~ing)  Date: 14th century  1. to adjust (a part or thing) in size relative to other parts or things  2. to make the parts of harmonious or symmetrical  3. apportion, allot