1
general::
1. The same number of. For example, He changed jobs four times in as many years means he changed jobs four times in four years. [c. 1400] 2. as many as. A phrase used to qualify the meaning of many as a very large number, depending on what follows it. For example, You can take as many pens as you need. [Late 1300s] Also see AS . . . AS; AS MUCH AS.
American Heritage Idioms