The Collaborative International Dictionary of English v.0.48:

Yalu \Ya"lu\, prop. n.
   A river in eastern Asia, which rises in North Korea and flows
   southwest to Korea Bay (forming part of the border between
   North Korea and China).

   Syn: Yalu River.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Yalu
    n 1: river in eastern Asia; rises in North Korea and flows
         southwest to Korea Bay (forming part of the border between
         North Korea and China) [syn: Yalu, Yalu River]