To put forth the utmost amount of energy or effort toward some task or goal. A more polite version of "do one's damnedest." Money is a little tight at the moment, but I'll do my darnedest to be there for your wedding.

To put forth the utmost amount of energy or effort toward some task or goal. A more polite version of "do one's damnedest." Money is a little tight at the moment, but I'll do my darndest to be there for your wedding.