1. might and main - Noun
2. might and main - Adverb
might and main (not comparable)
With all one's strength; as hard as one can.
might and main (uncountable)
All one's strength.
The manly part is to do with might and main what you can do. Ralph Waldo Emerson
All for each, and each for all, is a good motto; but only on condition that each works with might and main to so maintain himself as not to be a burden to others. Theodore Roosevelt
While the abominable pope with his spiritual peace and evangelic peace, this despot, marched to make war on his own kindred with might and main - the man of peace, too, and disciple of the Man of Peace! Anna Comnena