Came from the slave days, and was considered a medical disease which needed curing if a slave was wanting to escape. So, metaphorically speaking, this word can be used as a noun if you feel trapped and ache for escape. on Travel quotes quotes
"Parallel lines have a lot in common, but they never meet. You might think that's sad. But every other pair of lines meets once and then drifts apart forever. Which is pretty sad too." a little bit of mathematical insight about life stuff.