The Spanish verb 'ir' (to go) has a fascinating etymology as it is derived from three different Latin verbs that merged together: 'ire' (to go), 'vadere' (to go, advance), and 'esse' (to be). This is why 'ir' has such an irregular conjugation in Spanish - different forms come from different Latin sources. For example, the present tense forms like 'voy' (I go) come from 'vadere', while the imperfect 'iba' comes from 'ire', and forms like 'fui' (I went) come from 'esse'.

This combination of three verbs into one is a relatively rare phenomenon in language evolution called 'suppletion', where different forms of a single modern verb come from completely different ancestral verbs. It's similar to how in English, the verb 'to go' uses 'went' as its past tense, which historically comes from a different verb entirely.

Several common Spanish words are related to 'ir' through its Latin ancestors. The verb 'evadir' (to evade) comes from Latin 'evadere', which contains 'vadere'. Similarly, 'invasión' (invasion) and 'invadir' (to invade) are related through the same Latin root, literally meaning 'to go into'. From 'esse', we get Spanish words like 'ser' (to be), 'estar' (to be), and 'esencia' (essence).

Many English words are related to the Latin roots of 'ir'. From 'vadere', we get words like 'invade', 'evade', and 'wade'. From 'esse', we get words like 'essence', 'essential', 'present', and 'absent' (literally meaning 'being away'). The Latin 'ire' gives us words like 'exit' (to go out), 'initial' (going in), and appears in many words with '-ition' endings like 'transition' (going across).