Any of the (usually six) discrete, often papilliform, areas of columnar epithelium in the rectum of insects, serving chiefly to reabsorb water and salts.
Origin
1930s.
Definition of rectal pad in US English:
rectal pad
noun
Entomology
Any of the (usually six) discrete, often papilliform, areas of columnar epithelium in the rectum of insects, serving chiefly to reabsorb water and salts.