The Spanish word 'sustentable' (meaning 'sustainable') has its roots in Latin. It begins with the Latin prefix 'sub-' meaning 'under' and the verb 'tenere' meaning 'to hold'. These combined to form the Latin verb 'sustinere' meaning 'to hold up' or 'to sustain'. This then developed into the frequentative form 'sustentare' (indicating repeated or continuous action of sustaining) in Latin.

In Spanish, this evolved into the verb 'sustentar' ('to sustain'), and with the addition of the suffix '-able' (meaning 'capable of'), it formed 'sustentable', literally meaning 'capable of being sustained' or 'sustainable'.

Some related Spanish words that might be familiar to Spanish learners include 'sostener' (to hold up, to support), which comes from the same Latin root 'sustinere'. The verb 'sustentar' itself is also commonly used, meaning 'to sustain' or 'to support'. Another related word is 'sostenible', which is actually more commonly used than 'sustentable' to mean 'sustainable' in many Spanish-speaking countries.

English speakers can easily connect 'sustentable' to several English words that share the same Latin ancestry. The most obvious is 'sustainable', which is a direct equivalent. Other related English words include 'sustain', 'sustenance', 'sustainable', and 'maintain' (from Latin 'manu-tenere', meaning 'to hold with the hand'). The common thread among all these words is the idea of holding, supporting, or maintaining something over time.