"A fraction is a part of a whole"
http://www.mathsisfun.com/fractions.html
Imagine if you dropped your mom's favorite china plate on the floor, and it 'Fract'ured. Now imagine, to your mom's horror and amazement, that it fractured into 12 pieces of exactly the same size.
Each of these pieces would a "fraction" of the (former) whole plate--they'd each be one twelfth (1/12), to be exact.