balsa

 
Pronunciation: /ˈbɔːlsə, ˈbɒlsə/

noun

[mass noun]
  • 1 (also balsa wood) very lightweight timber used chiefly for making models and rafts.
  • 2the fast-growing tropical American tree from which this timber is obtained.
    • Ochroma lagopus (or pyramidale), family Bombacaceae

Origin:

early 17th century (denoting a kind of South American raft or fishing boat): from Spanish, 'raft'