The word overly sensitive linguists and people with a fixed attitude to language use (or pretensious posh people) use instead of quadrilogy, because quadrilogy is a mixture of Latin and Greek and therefore awfully awkward to say, darling.

Tetralogy is a word that means 'a series of four.'
Eg, "have you see any of the Alien tetralogy, I thought they were all totally nauseating, yah."
by SpiceofLife June 26, 2014
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