Precede, anticipate. (Latin præ-venio, to go before.) And as what goes before us may hinder us, so prevent means to binder or keep back.
“My eyes prevent the night watches.”- Psalm cxix. 148.
“Prevent us, O Lord, in all our doings.” —Common Prayer Book.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Prevent from Fact Monster: