Pahoehoe \Pa*ho"e*ho`e\, n. (Min.) A name given in Hawaii (formerly the Sandwich Islands) to lava having a relatively smooth or billowing surface, in distinction from the rough-surfaced lava, called {aa}. [1913 Webster +PJC]
There are two kinds of lava _ pahoehoe and a'a _ identical in chemical composition.
Most lava erupts as pahoehoe, with some changing to a'a as its temperature and gas content decrease.