The Collaborative International Dictionary of English v.0.48:
Capful \Cap"ful\, n.; pl. Capfuls. As much as will fill a cap. [1913 Webster] +PJC A capful of wind (Naut.), a light puff of wind. [1913 Webster]WordNet (r) 3.0 (2006):
capful n 1: the quantity that a cap will hold