Last summer I went to a talk where the speaker had a specific name for a certain kind of degenerated foliation on a manifold. Sadly, I forgot that name.
Question : what is that name ?
(Sorry if my question is vague)
e.g. If you look at the level sets of $f(x,y)= x^2-y^2$ on $\mathbb R^2$ you get that sort of degenerated foliation.
