Meaning & use
red blood
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Meanings
phraseuncountabletechnical
Blood that carries oxygen and looks bright red, as opposed to blood without oxygen, which looks darker.
Grammar: Used as an uncountable phrase; it does not take an or an and has no plural form.
Patterns
- red blood cells
- carry red blood
The doctor explained that red blood carries oxygen around the body.
In the diagram, red blood is shown flowing away from the heart.
A shortage of red blood cells can make you feel tired.
phraseuncountable
Used in everyday speech to mean blood that is truly red, especially in contrast with something pale or colorless.
Grammar: Uncountable; often used after verbs like see or draw when talking about real blood.
Patterns
- see red blood
- draw red blood
The nurse took a sample and the red blood filled the small tube.
He cut his hand badly and there was red blood everywhere.
Common combinations
- red blood cell
- Red blood cells carry oxygen from the lungs to the rest of the body.
- red blood count
- The lab reported a low red blood count.
- red blood cells in the urine
- The test found red blood cells in the urine.
- produce red blood cells
- Bone marrow produces red blood cells.
- a drop of red blood
- A single drop of red blood fell onto the white cloth.
Synonyms and how they differ
- blood
- The general word for the red liquid in the body; red blood is used when you want to stress its color or contrast it with other kinds of blood.
- erythrocytes
- The technical medical term for red blood cells, not for blood itself; use it only in scientific writing.
Word family
Commonly confused: red blood or red-blooded?
red blood vs red-blooded
Red-blooded is a single hyphenated adjective meaning full of energy or strong feeling, as in a red-blooded sports fan; it is not the same as the phrase red blood.
Practice
Which sentence uses the phrase 'red blood' correctly?
Choose one answer.
'Red blood' is an uncountable phrase, so it cannot take 'a' or a plural, and 'red-blooded' is a separate adjective; only the sentence about red blood cells uses the phrase correctly.
Make it your own
Write a sentence using “red blood”, then check it and compare it with the examples above.