noun which may take the genitive case particle 'no', na-adjective, noun
bloody; gory; covered in blood
Describes something physically covered or drenched in blood, often in a violent or gruesome context.
事故現場は血みどろだった。
The accident scene was bloody.
血みどろの包帯が落ちていた。
A blood-soaked bandage was lying there.
noun which may take the genitive case particle 'no', na-adjective, noun
Figurative use describing a situation or effort that is extremely intense, as if bloodied by struggle. Often used with 努力 (effort) or 戦い (fight).
血みどろの努力で試験に合格した。
I passed the exam through desperate effort.
彼は血みどろになって働いた。
He worked frantically, as if his life depended on it.
血まみれ also means 'covered in blood' but is more common and neutral; 血みどろ carries a stronger, more dramatic or gruesome nuance.
血 (blood) + みどろ, an old suffix meaning 'covered with' or 'drenched in', related to まみれる. The exact derivation is uncertain.