1. A cavern in the earth, whether natural or artificial.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• gritt,
• growt,
• gotta,
• gretta,
• gehtto,
• getto,
• ghotto,
• greato,
• gront,
• groto,
• grouo,
• gatto,
• guetto,
• gotte,
• govto,
• groath,
• groeth,
• growtth,
• grouth,
• grett

• gritty,
• groth,
• grout,
• grotty,
• grit,
• grate,
• garotte,
• grot,
• greet,
• groat,
• Gretta,
• grothe,
• grado,
• grode,
• griot,
• Grote,
• Greta,
• great.

The adjective form of the word "grotto" is "grottoed".