An adenocarcinoma that arises from the small intestine. Histologic variants include mucinous adenocarcinoma and signet ring cell carcinoma. The disease is small intestine adenocarcinoma (MONDO_0003198, a Monarch Disease Ontology identifier). Also known as: adenocarcinoma - small intest., adenocarcinoma of small bowel, adenocarcinoma of small intestine, adenocarcinoma of the small bowel, adenocarcinoma of the small intestine, small bowel adenocarcinoma, small intestinal adenocarcinoma.