A cavelet is a small cave large enough for a human to enter but too small to qualify as an official cave. It must have been formed by the same natural geologic processes qualifying caves are formed from.
Some small cave discoveries yield much larger caves upon closer inspection. Likewise it is probable that a certain percentage of cavelets have the potential to yield further discoveries (either be larger than they first appear or provide further clues about nearby karst).
References
Cavelet Wikipedia(Text) CC BY-SA