one’s bottom dollar

(one's) bottom dollar

1. The last dollar one has available to spend. I put my bottom dollar on that bet. If I lose this one, that'll be the end of my Vegas run. Sorry, dude, I can't loan you anything—I spend my bottom dollar on that sandwich.
2. A certainty that something will happen or be true. (Used almost exclusively in the phrase "bet (one's) bottom dollar.") I lost my umbrella, so you can bet your bottom dollar that it will rain tomorrow! Oh, I'd bet my bottom dollar that Kevin will be late tonight—he's never on time!
See also: bottom, dollar

one’s bottom dollar

n. one’s last dollar. (see also bet one’s bottom dollar.) I’m down to my bottom dollar. How about a little loan?
See also: bottom, dollar