Collar
Front Of The Neck, Nape Of The Neck
noun
The origin of your collar is your collar! And the nape of the neck because that's where collars go.
えりもと
The readings for this word are both kun'yomi readings. You've learned both of these readings by now so you should be able to read this on your own.
襟元にファンデーションがついていますよ。
There’s foundation on your collar.