The Spanish word 'libreta' (meaning 'notebook') comes from combining the Spanish word 'libro' (meaning 'book') with the diminutive suffix '-eta'. The word 'libro' itself comes from Latin 'liber', which also meant 'book'. So a 'libreta' is literally a 'little book', which evolved to specifically mean a notebook.

The most obvious related Spanish word is 'libro' (book), which is a very common and fundamental Spanish word. While 'libro' refers to any kind of book, 'libreta' specifically refers to a notebook or notepad - essentially a smaller, more specific type of book.

Several English words share the same Latin root 'liber', including 'library', 'librarian', and 'libretto' (the text of an opera). All these words maintain a connection to books or written materials. The word 'library' is particularly interesting as it's a place where books ('libros' in Spanish) are kept.