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Prepositions with nouns

Of defense or in defense?

In defense is a standard expression meaning 'supporting' or 'protecting'. Of defense is usually not a complete expression on its own, although it appears in longer noun phrases.

Quick answer

Use in defense for support or protection

Use in defense of when defending a person, action, or idea. Of defense is not usually used alone, but it appears in names and formal noun phrases such as Department of Defense.

The attorney spoke in defense of her client.
He wrote an article in defense of public libraries.
She works at the Department of Defense.

Choose the pattern by meaning

These forms are not interchangeable. Choose the construction by meaning, not by which preposition appears most often.

1
in defense of + person/idea

Supporting or protecting something

Use in defense of when arguing for or protecting someone or something.

Several witnesses testified in defense of the driver.
The editor wrote in defense of press freedom.
2
defense against + threat

Protection from danger

Use against to identify the attack, risk, or danger.

The system provides defense against cyberattacks.
Exercise is a good defense against stress.
3
defense of + noun

Formal noun structures

Defense of can refer to the act of defending a place, principle, or person.

The defense of the coast was well organized.
They discussed the defense of civil rights in class.

See the difference in context

The same subject can take different constructions because each sentence answers a different question.

Construction
Example
Meaning
in defense of
She spoke in defense of the decision.
A standard phrase for support or protection.
of defense
the Department of Defense
Part of a larger title or noun phrase, not usually a complete expression by itself.
defense against
The software is a defense against viruses.
Shows what danger is being resisted.
defense of
The defense of democracy became a major issue.
A formal structure referring to the act of defending something.

Common mistakes

Some combinations appear in real text but do not mean what learners often assume.

Using of defense as a fixed phrase

Of defense usually needs a larger noun phrase around it.

✕ She spoke of defense her brother. ✓ She spoke in defense of her brother.

Leaving out of after in defense

The normal structure is in defense of someone or something.

✕ He argued in defense the proposal. ✓ He argued in defense of the proposal.

Mixing up defense against and in defense of

Against introduces a threat, while in defense of introduces the thing supported.

✕ The medicine works in defense of infection. ✓ The medicine works as a defense against infection.

Quick practice

Choose the expression that matches the intended meaning.

1. The mayor spoke ___ defense of the new policy.
2. This spray offers defense ___ insects.
3. She works for the Department ___ Defense.

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Frequently asked questions

What does in defense of mean?

It means supporting, protecting, or justifying someone or something.

Can defense be followed by against?

Yes. Defense against is common when talking about protection from attacks, illness, or threats.

Is of defense correct?

Usually not as a complete phrase. It is mainly used inside longer noun phrases such as Department of Defense.

of, about, against, to or for racism? of, about, for, in or on friendship? of, about, for, on or to thing? of, about, for, to or with sex? of, about, on, to or for moon? "of access" or "with access"? "of accommodation" or "for accommodation"? "of accuracy" or "for accuracy"? "of action" or "in action"? "of actor", "with actor" or "by actor"? "of address" or "to address"? "of administration" or "in administration"?

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