The Spanish word 'ineficiencia' (meaning 'inefficiency') comes from combining the Latin prefix 'in-' (meaning 'not') with 'eficiencia' ('efficiency'). The word 'eficiencia' itself derives from the Latin 'efficientia' (meaning 'effectiveness'), which was formed from the Latin prefix 'ex-' (meaning 'out') and the verb 'facere' (meaning 'to do, make'). The evolution from Latin to Spanish shows how the concept of 'doing something effectively' (literally 'doing outward') became negated to mean 'lack of efficiency' or 'wastefulness'.

Some simpler related Spanish words include 'hacer' (meaning 'to do/make'), which comes from the same Latin root 'facere'. The word 'eficaz' (meaning 'effective') is also related, sharing the same Latin roots of 'ex-' and 'facere'. These connections help show how the idea of 'doing' or 'making' is fundamental to the concept of efficiency.

English speakers can recognize the connection to words like 'efficient', 'inefficient', and 'effectiveness', which share the same Latin origins. The English word 'fact' also comes from Latin 'facere', showing how something that is 'done' or 'made' became associated with truth or reality. Other related English words include 'effect' (literally meaning 'to work out') and 'affect', all stemming from the basic idea of 'doing' or 'making' something.