When you have a situation for which there is only one choice, that you have to do. You don't really want to do it, but there's no choice.
As opposed to a dilemma when you have two choices for a situation.
"Last night I had to go see the 12:01 showing of Green Hornet. The only time I could see it. I didn't want to, but I had to. Eh, I'm in a real lemma." Ben Mankiewicz, the What the Flick?! movie review show
(noun) A slang word that is used when talking about an issue, problem, or dilemma, but don't want to use a word as harsh. The meaning is similar, but the connotation is lighter.
This word is similar to "dilemma", but is not derived from that word.
A very great technique for solving math problems. Often only works because they solved it in a different way and used this lemma in a way that gives the same answer as the other way.