IPA: /ˌpɛrəˈtoʊnɪəli/
KK: /ˌpɛrəˈtoʊnɪəli/
In a manner that involves the peritoneum, which is the membrane lining the abdominal cavity.
The medication was administered peritoneally to ensure it reached the intended area quickly.
Peritoneally → It is formed from "peritoneum" (from Latin *peritoneum*, meaning the membrane lining the abdominal cavity) and the suffix "-ally" (meaning in a manner relating to). The word "peritoneally" refers to something that is done in a manner relating to the peritoneum, typically in a medical context.
Think of the peritoneum as the membrane that lines the abdomen, and remember that 'peritoneally' means something done in relation to that membrane.