The Collaborative International Dictionary of English v.0.48:
Haymow \Hay"mow`\ (h[=a]"mou`), n. 1. A mow or mass of hay laid up in a barn for preservation. [1913 Webster] 2. The place in a barn where hay is deposited. [1913 Webster]WordNet (r) 3.0 (2006):
haymow n 1: a mass of hay piled up in a barn for preservation 2: a loft in a barn where hay is stored [syn: hayloft, haymow, mow]