Only when written 首 / 頸 / 頚
The physical neck; the part of the body connecting the head and torso.
He has a scarf wrapped around his neck.
Only when written 首 / 頸 / 頚
Refers to the head, especially in contexts of decapitation or when the head is considered together with the neck. Often used in set phrases like 首を切る (to behead) or 首をかしげる (to tilt one's head in puzzlement).
He tilted his head in puzzlement.
Colloquial term for being fired or laid off from a job. Often used in the phrase 首になる (to be fired) or 首にする (to fire someone). The katakana spelling クビ is very common for this sense.
He was fired for being late too often.
The company fired several people to cut costs.
He shook his head in response to the question.
In the past, criminals were sometimes beheaded.
The culprit strangled the victim's neck.
She tilted her head, puzzled by the story.
He wears his employee ID hanging around his neck.
He hanged himself in despair.
くびれ (a narrow constriction, like a waist) is easily confused by sound with 首 (neck), a body part, though the two words are unrelated in meaning.
animal collar · necklace; choker
nape of the neck; back of the neck; scruff of the neck
hanging oneself; suicide by hanging
freshly severed head
necklace; choker
decapitation; beheading · firing; dismissal; layoff; downsizing · small decapitation sword
head over heels in love; madly in love; crazy about
scruff of the neck
decapitation; beheading
hanging; death by hanging
bowl and shank of a Japanese pipe · neck; head
head
nape of the neck
head of a sleeping person
round neck; crew neck
bull neck; thick neck
low-class prostitute; woman with white-powdered neck
ear of rice; head of a rice plant; spike
head (derogatory)
wrist
falsified severed head
sickle-shaped neck; crooked neck; gooseneck
base of the throat; bottom of the neck
burial mound for severed heads
Rare kanji specifically for dismissal; almost never used in modern writing.
Rare kanji variant for neck; mostly seen in medical or formal contexts.