Refers to the area around the mouth, including the lips, often in contexts of expression, eating, or appearance.
She covered her mouth as she laughed.
She laughed, covering her mouth with her hand.
You have some food around your mouth.
shape of the mouth
Describes the form or contour of the mouth, often when discussing facial features or expressions.
The shape of his mouth always gives a gentle impression.
near an entrance; vicinity of an entrance
Used for the area just inside or outside an entrance, such as a doorway or gate. Often appears in set phrases like 口元まで来る.
I came up to the entrance, but didn't have the courage to go inside.
His mouth broke into a smile when he heard the story.
The ship had come up to the mouth of the harbor.
唇 names the lips as a body part, whereas 口元 covers the lips plus the surrounding area and the overall look or movement of the mouth.
顎 is the specific anatomical jaw or chin, while 口元 more loosely describes the area around the mouth including lips and chin.
Standard kanji spelling.
Mixed kana-kanji spelling, common in everyday writing.
Rare kanji variant using 許; not commonly used.
Compound of 口 (kuchi, 'mouth') and 元 (moto, 'origin, base, vicinity'). The 'entrance' sense is a figurative extension of 'mouth' as an opening.