1. The scientific study of caves, , especially in respect of their geological formation, flora, fauna etc.
2. The the sport or pastime of exploring caves; caving.
First coined, according to the OED, by EA Martel in the Report of the 6th Geographical Congress of 1895.
Hence speleological, of or pertaining to speleology; speleologist, a student of, or authority on, cave-research; an explorer of caves.