The Spanish word 'ocular' comes from the Latin word 'ocularis', meaning 'relating to the eyes'. This Latin word was formed by combining 'oculus' (meaning 'eye') with the relational suffix '-aris', which was used to create adjectives indicating a relationship or connection to something. The word maintained its meaning and similar form as it evolved from Latin to Spanish.

Some related Spanish words include 'ojo' (eye), 'oculista' (eye doctor/ophthalmologist), and 'binocular' (binocular). All these words share the same Latin root 'oculus' meaning 'eye'. While 'ocular' refers specifically to something relating to the eyes, 'ojo' is the common everyday word for eye itself.

Several English words share this same Latin root, including 'ocular' (which is identical to the Spanish word), 'oculist' (an archaic term for eye doctor), and 'binocular'. The word 'oculus' is also used in English architecture to refer to a circular window or opening, maintaining a connection to the original Latin meaning of 'eye'. The similarity between English and Spanish 'ocular' makes this word particularly easy for English speakers to remember.