The Spanish word 'tigresa' (meaning 'tigress') comes from combining the Spanish word 'tigre' ('tiger') with the feminine suffix '-esa'. The word 'tigre' itself can be traced back to Latin 'tigris', which was borrowed from Ancient Greek 'τίγρις' (tigris), both meaning 'tiger'. The feminine suffix '-esa' is used in Spanish to form feminine nouns, especially for animals and professions.

The most obvious related Spanish word is 'tigre' (tiger), which is the masculine form and more commonly encountered word. This is the base word to which the feminine suffix '-esa' was added to create 'tigresa'. Other Spanish words that use the same feminine suffix pattern include 'princesa' (princess), 'alcaldesa' (female mayor), and 'duquesa' (duchess).

The English word 'tiger' is closely related to 'tigresa', as both ultimately come from the same Greek source 'τίγρις' (tigris). English also borrowed this word through Latin. You can also see the connection to the English word 'tigress', which follows a similar pattern of adding a feminine suffix (-ess in English, compared to -esa in Spanish) to the masculine form.