Extremely strong or potent. Its original sense refers to the alcohol content of liquor. This cleanser is 110 proof. If it can't get the stain out, nothing can.

An effort towards something that is greater than one believes one is capable of doing, i.e., beyond 100% of one's ability; often used as a motivation in sports. Primarily heard in US. Alright guys, we all need to dig deep for the second half of the game. Go out there and give a hundred and ten percent and bring home a win!

To put forth the absolute maximum amount of effort or energy possible (i.e., even more than is usually required or seems possible). We're going to have to give 110% if we want to get this project finished by the deadline. A win today secures our spot in the championship, so go out there and give 110%!