Wordnet 3.0
NOUN (2)
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]
2.  a battle in the Korean War (November 1950);  when UN troops advanced north to the Yalu River 200,000 Chinese troops crossed the river and drove them back; 
WordNet (r) 3.0 (2006):
Yalu River
    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]
    2: a battle in the Korean War (November 1950); when UN troops
       advanced north to the Yalu River 200,000 Chinese troops
       crossed the river and drove them back