might and main

Etymology
A reduplication of two words meaning.

Adverb

 * 1) With all one's strength; as hard as one can.
 * 2) * c.1890s, Giovanni Boccaccio, James McMullen Rigg (translator), The Decameron, Novel 1, 6,
 * he strove might and main to pass himself off as a holy man
 * he strove might and main to pass himself off as a holy man

Noun

 * 1) All one's strength.