The Spanish word 'bolillo' comes from the word 'bolo' meaning 'pin' or 'bowling pin', combined with the diminutive suffix '-illo' to mean 'small pin' or 'stick'. The word 'bolo' itself derives from 'bola' meaning 'ball', which ultimately comes from Latin 'bulla' meaning 'bubble' or 'ball'. This evolution shows how the meaning shifted from a round shape to a more elongated pin-like form, with the diminutive suffix adding the sense of smallness.

Some simpler Spanish words that share this etymology include 'bola' (ball) and 'bolo' (pin, bowling pin). These words are easier to remember as they show the progression from a round shape ('bola') to the pin-like shape ('bolo'), before getting to the diminutive form 'bolillo'.

While not directly cognate, English words related to the Latin root 'bulla' include 'bull' (in the sense of an official document with a seal, which originally referred to the round seal itself), 'bulletin' (originally a small sealed document), and 'bubble'. These words all share the connection to roundness or swelling that characterized the original Latin word.