Unusual mathematical terms From time to time, I come across some unusual mathematical terms. I know something about strange attractors. I also know what Witch of Agnesi is. However, what prompted me to write this question is that I was really perplexed when I read the other day about monstrous moonshine, and this is so far my favorite, out of similar terms.
Some others:


*

*Cantor dust

*Gabriel's Horn (also known as Torricelli's trumpet)

*Koch snowflake

*Knaster–Kuratowski fan (also known as Cantor's leaky tent or Cantor's
teepee depending on the presence or absence of the apex; there is also Cantor's leakier tent)


Are there more such unusual terms in mathematics?

Jan 17 update: for fun, word cloud of all terms mentioned here so far:

and another, more readable:


A Killing field is not as bloody as it sounds; it's actually a certain type of vector field named after Wilhelm Killing.
