The Collaborative International Dictionary of English v.0.48:

Percentage \Per*cent"age\ (p[~e]r*s[e^]nt"[asl]j), n. [Per cent
   + -age, as in average. See Per, and Cent.] (Com.)
   A certain rate per cent; the allowance, duty, rate of
   interest, discount, or commission, on a hundred.
   [1913 Webster]

WordNet (r) 3.0 (2006):

percentage
    n 1: a proportion in relation to a whole (which is usually the
         amount per hundred) [syn: percentage, percent, per
         centum, pct]
    2: assets belonging to or due to or contributed by an individual
       person or group; "he wanted his share in cash" [syn: share,
       portion, part, percentage]