Etymology:
< Spanish guayabera (1888 or earlier in this sense), of uncertain origin, perhaps ultimately showing a derivative of either guayaba guava or guayabo guava tree.
Chiefly U.S.
A lightweight, loose-fitting shirt
for men, typically having two breast pockets and two lower front
pockets, a number of vertical pleats, and short sleeves, and usually
worn untucked. (OED)
"A slim, friendly man with a shaved head, Rodríguez was derssed in the informal manner of many of Chávez's ministers: a crisp white guayabera over black jeans and running shoes."
- Jon Lee Anderson, "Slumlord: What has Hugo Chávez wrought in Venezuela?", 28 January 2013 The New Yorker