The Spanish word 'fluorescente' comes from the Latin word 'fluorescens', which was formed by combining three elements: the root 'fluor' meaning 'flow' or 'flux', the process suffix '-sc-', and the present participle suffix '-nt-'. The '-sc-' suffix in Latin typically indicated the beginning or ongoing process of something, while '-nt-' marked it as a present participle, meaning 'becoming' or 'in the process of'. Together, these elements created a word describing something in the process of flowing or emitting flux, which evolved to describe the emission of light we now know as fluorescence.

A related Spanish word is 'fluir' (to flow), which comes from the same Latin root 'fluor'. While 'fluir' maintained the basic meaning of flowing like a liquid, 'fluorescente' developed to specifically describe the emission of light. Another related word is 'flúor' (fluorine), the chemical element named for its flowing properties.

The English word 'fluorescent' is a direct cognate of the Spanish 'fluorescente', sharing the same Latin origin. Other related English words include 'fluid' and 'flux', both derived from the Latin 'fluor'. While 'fluid' refers to something that flows like a liquid and 'flux' refers to continuous change or flow, 'fluorescent' specifically developed to describe materials that emit light when exposed to radiation.