To discomfit is to embarrass someone. Say it with a Southern accent while sipping sweet tea. Discomfort is a noun meaning uncomfortable, like the feeling you get when you realize you put salt instead of sugar in Mama's tea.

Discomfit is a verb that began as "to defeat in battle," but now it means to rattle or embarrass someone. It's so embarrassing to lose! This "newer" definition (it's been in action since about 1400, says The Oxford English Dictionary) came to be when people got it confused with discomfort. How embarrassing! Here are some discomfits undoing folks in the news:

But today even the best zoos discomfit many parents, this one included. (Time)

At the same time, the Obama administration is pressing for changes that could discomfit the king and his aides. (Los Angeles Times)

Discomfort is a noun meaning physical or mental distress. That's how it stays away from its sound-alike; it's rarely used as a verb anymore. Like all nouns, you can put an a, an, or the in front of it an it makes sense:

Yoga can help alleviate some of the discomforts of pregnancy and keep mothers-to-be fit. (Fit Pregnancy)

Nabokov said he sustained an injury during the first period, played through the discomfort, but "Jack pulled the trigger" to substitute DiPietro. (New York Times)

Use discomfit to embarrass; use discomfort for embarrassment. Taste that tea before you serve it if you want to avoid both.