Your dictionary defines "brave" as "courageous", and "courageous" as "brave". That's a circular definition.

I changed the definition of "sex" from "to have sex" to "to have sexual intercourse"; a dictionary definition must never be circular; using the word being defined to define itself.

A man so absolute and circular / In all those wished-for rarities that may take / A virgin captive.

February 1, 1711, John Dennis, on the Genius and Writings of Shakespeare
Had Virgil been a circular poet, and closely adhered to history, how could the Romans have had Dido?

The result of the sending of these notices confirms me in the opinion, that it will be necessary to adopt legal means with the great majority of these parties. The circulars have had little effect. In fact, the parties have been “circulared" into the notion that nothing more formidable will ever be sent to them.

It is true, that, to obtain these, some six hundred or more institutions were circulared, and a good many of these a second time.

I do not mean to say we have never employed some of them who come to us—but we have never circulared agents or gone after them.

If you've ever been circulared by drug repackaging houses, you know they usually offer to trade a selection of office supplies for your unused drug samples.

The theme can be expressed in an architectural analogy. For, of all contriving to encover space, the arch — alone or 'circulared' into the dome — is the most ingenious.

Circular

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