'विपरीत' has a very nice etymology: vi - away, pari - (cognate with Greek peri-) around, surrounding, and ita - gone. "Gone beyond the surrounds or perimeter", i.e "excessive". Similarly, 'vIta' is 'gone away' or 'lacking', as in 'vItarAga' (lacking in desires). Similarly atIta 'exceeded', adhIta 'attained'.
'e' is cognate with Latin 'eo', which also means 'to go'. No discussion on this topic is complete without Monty Python's take on it :-)