noun
suet
SOO-it/ˈsuːɪt/
Hard fat from around an animal’s kidneys and loins, used in cooking or bird feed.
The hard white suet sits beside a seed-filled cake made from the same fat.

Etymology
Suet probably comes from a diminutive of Old French siu, “fat” or “tallow.” The English word names specifically the solid fat found in the torsos of cattle and sheep.
In context
if that's something that you're interested in learning more about, I'll definitely link to those videos in the description below, where I show you not only how to render beef suet and make tallow, but then how to use tallow
More examples
- The butcher trims the suet from around the beef kidneys.
- She grates cold suet into the dough for dumplings.
- We mix melted suet with seeds for the birds.