One verb in this Dagestani language has 1.5 million possible forms

Archi, spoken by about 1,200 people in the Caucasus mountains of Dagestan, marks its verbs for person, number, gender, tense, aspect, mood, and evidentiality, all layered together. Linguists calculated that a single regular Archi verb can take roughly 1.5 million distinct forms, making it one of the most complex morphological systems ever documented.

— Marina Chumakina, Greville G. Corbett (editors), Archi: Complexities of Agreement in Cross-Theoretical Perspective — Oxford University Press / British Academy, 2013
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