洞窟|どうくつdoukutsu[0]heiban (flat)

1. nouncave; cavern; grotto
   これは私が洞窟どうくつの中なかで見みつけたものです。↗

   This is what I found in the cave.

• Synonym洞穴ほらあなNeutralA general word for caves; interchangeable with 「洞窟」, though 「洞窟」 is more common and stresses depth, often in archaeology, exploration and sightseeing contexts.
• Synonym岩屋いわやNeutralA natural rock cave, also a dwelling carved into rock; 「洞窟」 is more common.
• Synonym岩窟がんくつWrittenWritten/formal prose for a cave in rock; 「洞窟」 is not limited to rock.
• Related岩穴いわあなNeutralA hole in rock, used rarely; 「洞窟」 broadly covers deep holes in cliffs and rock.
• Related岩室いわむろWrittenWritten/formal prose for a natural rock cave resembling a room; in everyday speech, say 「洞窟」.

For caves in general, 「洞窟」 is the default; 「洞穴」 is an interchangeable alternative. For caves in rock, use 「岩穴」 or the formal 「岩窟」, and for rock caves used as dwellings, 「岩屋」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 崖がけや岩石がんせきにできた奥行おくゆきの深ふかい穴あな。