The Spanish word 'hilito' meaning 'little thread' comes from the Spanish word 'hilo' (meaning 'thread') combined with the diminutive suffix '-ito'. The base word 'hilo' itself derives from Latin 'filum', which also meant 'thread'. The change from Latin 'f-' to Spanish 'h-' is a common sound change that occurred in the development of Spanish from Latin. The diminutive suffix '-ito' is a very productive suffix in Spanish that adds the meaning of 'small' or 'little' to the base word.

The simpler and more common Spanish word 'hilo' is directly related to 'hilito', as it is the base word from which 'hilito' is formed. While 'hilo' means 'thread', adding the diminutive suffix '-ito' creates the more specific meaning of 'little thread'. Spanish students might also encounter this word in compounds like 'hilador' (spinner) or 'hilar' (to spin thread).

English speakers might recognize the connection to words like 'filament' and 'file' (as in single file), which also come from the Latin word 'filum'. A filament is a thread-like structure (as in a light bulb), while the concept of a single file line relates to people forming a thread-like arrangement. The word 'profile' also contains this root, originally referring to the outline or thread-like edge of something.