also: ちにく
noun
blood relative; one's own flesh and blood
Refers to a person who is related by blood, emphasizing a deep, natural bond. Often used in emotional or dramatic contexts.
彼は私の血肉の兄弟だ。
He is my flesh-and-blood brother.
親子は血肉を分けた間柄です。
Parent and child are bound by blood.
noun
Literally the physical body; also used metaphorically for something that becomes part of one's being, such as knowledge or experience.
その経験は私の血肉となった。
That experience became part of me.
読書で得た知識が血肉になる。
Knowledge gained from reading becomes flesh and blood.
Compound of 血 (blood) and 肉 (flesh). The metaphorical extension to 'blood relative' and 'integral part of oneself' is natural given the physical components of the body.