The Spanish verb 'rebuscar' (meaning 'to search thoroughly') is formed by combining two elements: the Latin prefix 're-' meaning 'again' or 'back', and the Spanish verb 'buscar' meaning 'to search' or 'to look for'. The prefix 're-' intensifies the meaning of 'buscar', suggesting a more thorough or repeated search, similar to how we might say 'to search and search again' or 'to search thoroughly'.

The most obvious related Spanish word is the simpler and more common verb 'buscar', which means 'to search' or 'to look for'. This is the base verb from which 'rebuscar' is formed. While 'buscar' refers to a general search, 'rebuscar' implies a more intensive or thorough searching action.

While English doesn't have a direct cognate of 'buscar' or 'rebuscar', English speakers will recognize the prefix 're-' from many English words like 'repeat', 'return', and 'review', where it carries the same meaning of 'again' or 'back'. This shared Latin prefix helps make the intensifying meaning of 'rebuscar' more intuitive for English speakers.