The Spanish word 'vesícula' (meaning 'vesicle') comes from the Latin word 'vesicula', which meant 'small bladder'. The Latin 'vesicula' was formed by combining two parts: 'vesica' (meaning 'bladder') and the diminutive suffix '-ula'. This suffix '-ula' was commonly used in Latin to create words indicating something smaller than the base word, so 'vesicula' literally meant 'little bladder'.

This etymology reflects how vesicles are small, sac-like structures in biology, maintaining the connection to the original Latin meaning of a small bladder or sac.

A related Spanish word is 'vejiga' (meaning 'bladder'), which also comes from the Latin 'vesica'. While 'vejiga' refers to the entire bladder organ, 'vesícula' refers to smaller, bubble-like structures, staying true to its diminutive origins.

English speakers might recognize the connection to the word 'vesicle', which is directly related and has the same meaning as Spanish 'vesícula'. Both come from the same Latin source. The English words 'vesicular' (relating to or characterized by vesicles) and 'vesicant' (causing blisters) are also related, all sharing the connection to the concept of small fluid-filled sacs or bladder-like structures.