The Spanish word 'bolilla' comes from the combination of 'bola' (meaning 'ball') and the diminutive suffix '-illa'. The word 'bola' itself derives from Latin 'bulla', which meant 'bubble' or 'ball'. When the diminutive suffix '-illa' is added to 'bola', it creates the meaning of 'small ball'.

A simpler and more common Spanish word that's related to 'bolilla' is 'bola', meaning 'ball'. This is actually the base word from which 'bolilla' is formed. You might also encounter words like 'boliche' (bowling alley or bowling pin) and 'bolita' (another way to say 'small ball'), which come from the same root.

While not directly related, English speakers might find it helpful to know that the word 'bull's-eye' (originally referring to a round target) and 'bulletin' (originally a sealed document with a round seal) both come from the same Latin root 'bulla' as 'bolilla'. The round shape connection helps explain these relationships. Another related English word is 'bowl', which shares the idea of roundness or curved shape.