spelunk

Reader's Digest Julyの記事、Stuck in an Ice Cave、に出て来た見慣れない単語を取り上げます。
All told, the guys weren't seriously injured, and the incident hasn't diminished their love of spelunking. They even plan to return to the caves this summer.
"spelunking" を辞書で調べます。
・Vocabulary.com: To spelunk is to explore natural caves. Geologists do a lot of spelunking.
This is a weird-looking word, but it has a simple meaning: to explore natural caves. Scientists who study natural formations of the Earth do a lot of spelunking. Through spelunking, you can find evidence of difference(sic) minerals, as well as fossils of various animals. Archaeologists spelunk to find remnants of previous civilizations. Some people spelunk as a hobby: they are spelunkers.
・Urban Dictionary: the exploration of natural caves: Bat researchers usually spelunk many caves to find their information.
Urban Dictionaryから引用したからといって "spelunk" はスラングではありません。例文が載っている辞書が他にはほとんどなかったので引用したのです。ラテン語、古仏語由来の外来語でした。