Literary or old-fashioned word for a woman's breast, often with a soft or poetic nuance. Not used in modern everyday conversation.
upper neck joint of a shamisen
Refers to the rounded part at the top of a shamisen's neck. Usually written in kana.
In old waka poems, the word 乳袋 is used.
The ちぶくろ of a shamisen is the rounded part just below the tuning pegs.