The Spanish verb 'ensañar' (meaning 'to enrage' or 'to infuriate') comes from the Latin verb 'insaniare' meaning 'to make mad.' This Latin verb was formed from 'insania' ('madness'), which itself was built from three parts: the prefix 'in-' (meaning 'not'), the root 'sanus' ('healthy' or 'sane'), and the abstract noun suffix '-ia'. So literally, 'insania' meant 'the state of not being sane.' The Latin verb 'insaniare' was created by adding the verb suffix '-are' to 'insania'.

Over time, as the word evolved from Latin to Spanish, 'insaniare' became 'ensañar', with the 'in-' prefix changing to 'en-' (a common change in Spanish), and the meaning narrowed from general madness to specifically focusing on rage or fury.

The Spanish word 'sano' (meaning 'healthy' or 'sound') is related to 'ensañar' as they both come from Latin 'sanus'. While 'sano' retained the positive meaning of health and soundness, 'ensañar' developed from its negative form with 'in-' to describe the loss of mental soundness through rage.

Another related Spanish word is 'insano' (meaning 'insane' or 'unhealthy'), which more directly preserves the original Latin formation and meaning.

English speakers can connect 'ensañar' to several familiar words that share the Latin root 'sanus'. The most obvious are 'sane' and 'insane', which come directly from Latin 'sanus' and 'insanus'. The English word 'sanity' is also related, coming from Latin 'sanitas' (health of mind).

Understanding this connection can help remember that 'ensañar' deals with a loss of mental control through rage, just as 'insane' refers to a loss of mental soundness.