Curve
Curved Line
noun
A bend in a line is merely a curve.
きょくせん
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
このドレスは、曲線を美しく出してくれます。
This dress gives me beautiful curves.
ブーメランパンツから出てるコウイチのおしりの曲線…いいね！
The curve of Koichi's butt protruding from the speedo is very... nice!
あなたが怒った時の、ほおの柔らかく歪んだ曲線が好きよ。
I really love the soft, slanted curve of your cheek when you get mad.