suet

Etymology

From Middle English suet, sewet, borrowed from Anglo-Norman suet, siuet, from Old French seu, from Latin sebum.

noun

1. The fatty tissue that surrounds and protects the kidneys; that of sheep and cattle is used in cooking and in making tallow.
   Many seed-eating birds also need animal fat and protein which they obtain from insects, animal carcasses, and suet. 1996, Laura Erickson, Sharing the Wonder of Birds with Kids
   Some jays, chickadees, nuthatches, and titmice regularly feed at suet; others seem never to indulge. 1998, Alan Pistorius, Everything You Need to Know About Birding and Backyard Bird Attraction