1. noun /ˈfræk.ʃən/
a) A part of a whole, especially a comparatively small part.
With fresh material, taxonomic conclusions are leavened by recognition that the material examined reflects the site it occupied; a herbarium packet gives one only a small fraction of the data desirable for sound conclusions. Herbarium material does not, indeed, allow one to extrapolate safely: what you see is what you get
b) A ratio of two integers, the numerator and the denominator, usually written one above the other and separated by a vinculum (horizontal bar) <!rational number (a rational number can always be expressed as a fraction, but that does not make it same thing)
2. verb /ˈfræk.ʃən/
To divide or break into fractions.
Wikipedia foundation.