The Spanish word "guayaba" (meaning "guava fruit") comes directly from the Taíno language. The Taíno were indigenous people of the Caribbean, and many words for local fruits and plants entered Spanish through contact with their language during the early colonial period of the Americas. The word maintained both its form and meaning as it was borrowed from Taíno into Spanish.

Since "guayaba" is borrowed directly from Taíno, there aren't any etymologically related simpler Spanish words. However, you might encounter related derivative words like "guayabal" (a guava orchard) or "guayabera" (a type of shirt traditionally made in guava-growing regions).

The English word "guava" is actually related to "guayaba," as it also comes from the Taíno word, though it entered English through Spanish. The English version simplified the pronunciation by dropping the 'b' sound. This is a good example of how words for New World items often entered both English and Spanish through indigenous American languages.