The Spanish word 'piedrita' meaning 'small stone' comes from combining the Spanish word 'piedra' (stone) with the diminutive suffix '-ita'. The word 'piedra' itself has ancient roots, deriving from Latin 'petra', which in turn came from Ancient Greek 'πέτρα' (petra), both meaning 'rock' or 'stone'. The Latin word evolved into Spanish 'piedra' through a common sound change where the 'e' became 'ie' in stressed syllables. The addition of the diminutive suffix '-ita' creates the meaning of 'little stone'.

The most obvious related Spanish word is 'piedra' (stone), which is the base word from which 'piedrita' is formed. Understanding this relationship is straightforward - 'piedrita' is simply a small 'piedra'. The '-ita' suffix is very common in Spanish and is used to form diminutives, making it easy to recognize that this word means 'little stone'.

Several English words share the same Greek-Latin origin as 'piedrita'. The word 'petrify' (to turn to stone) comes directly from the Latin 'petra'. Other related English words include 'petroleum' (literally 'rock oil'), 'petrology' (the study of rocks), and 'saltpeter'. The name 'Peter' also shares this etymology, as it comes from the Greek 'Petros', meaning 'stone' or 'rock'.