Speluncar is a rarely used word that means "cave" or "cavern." However, there are many synonyms that can be used to describe a cave, which can help to enrich one's vocabulary. For example, one alternative term for a cave is "grotto," which is often associated with mystical or sacred spaces. Another option is "subterranean chamber," which emphasizes the underground location of the cave. "Underground cavern," "lair," and "underworld" are a few more synonyms that can be used to describe a cave. Utilizing these alternative words can help to convey a more specific or evocative sense of the cave being described.