Compound of 土俵(どひょう) (dohyō, “sumo ring”) + 入(い)り (iri), the 連(れん)用(よう)形(けい) (ren'yōkei, “stem or continuative form”) of the verb 入(い)る (iru, “come in”).
土(ど)俵(ひょう)入(い)り • (dohyōiri)