ETYM Spanish or Portu. balsa.
1. Forest tree of lowland Central America having a strong very light wood; used for making floats and rafts and in crafts; SYN. Ochroma lagopus.
2. Strong lightweight wood of the balsa tree used especially for floats; SYN. balsa wood.

A small raft or boat; specifically; one made of tightly bundled reeds and used on Lake Titicaca