n. 25B6; noun CAVERN, grotto, pothole, underground chamber.
speleology, speleologist; N. Amer. spelunking.
25A0; cave in
the roof caved in : COLLAPSE, fall in/down, give (way), crumble, subside.
the manager caved in to their demands : YIELD, surrender, capitulate, give in, back down, make concessions, throw in the towel/sponge.