Fat
Grease, Blubber
noun
Something that's both fat and obese has even more fat on it than you first thought. Like the blubber on a really big whale.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
太ももの脂肪を落としたいんです。
I want to lose the fat from my thighs.