blood clot; clot of blood
Refers to a mass of coagulated blood, either inside the body or outside. Can be used literally or figuratively to describe something that feels like a hardened lump of blood.
傷口から血の塊が出てきた。
A blood clot came out of the wound.
医者は血管の中の血の塊を取り除いた。
The doctor removed the blood clot from the blood vessel.
Compound of 血 (chi, 'blood') + の (no, possessive particle) + 塊 (katamari, 'lump, mass'). The meaning is transparent from its components.