The Spanish word 'tatarabuelo' meaning 'great-great-grandfather' is a compound word formed from two parts: the prefix 'tatara-' meaning 'great-great-' and 'abuelo' meaning 'grandfather'. The 'abuelo' portion has its origins in the Latin word 'avus' (grandfather), which evolved into the Vulgar Latin diminutive form 'aviolus' before becoming 'abuelo' in Spanish.

The most obvious related Spanish word is 'abuelo' (grandfather), which is directly contained within 'tatarabuelo'. The prefix 'tatara-' is also used in other family relationship terms like 'tataranieto' (great-great-grandchild) and 'tataranietro' (great-great-grandson).

While English doesn't have any direct cognates of 'tatarabuelo', the Latin root 'avus' is related to words like 'avuncular' (meaning 'like an uncle' or 'uncle-like'), which comes from the related Latin word 'avunculus' meaning 'maternal uncle'. This shows how family relationship terms often share ancient roots across different languages.