Waist
noun
The kanji and the word are exactly the same. That means they share meanings as well.
こし
The reading is the same as what you learned with the kanji.
あのバッターは腰が強い。
That batter has a strong waist.
腰に力を入れて立ってください。
Please put strength in your waist when standing.
腰に激痛が走ってるんだ。もう一歩も歩けないよ。
My waist is in intense pain. I can’t take another step.