(4 syl.). Heavy and ungainly, like an elephant. In Rome, the registers of the senate, magistrates, generals, and emperors were called elephantine books, because they were made of ivory. In geology, the elephantine period was that noted for its numerous large thick-skinned animals. The disease called elephantiasis is when the limbs swell and look like those of an elephant more than those of a human being.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894