circular

Etymology

From Middle English circuler, circuleer, circulere, from Old French circulier, from Late Latin circularis, from Latin circulus, diminutive of circus (“ring”).

adj

1. Of or relating to a circle.
2. In the shape of, or moving in a circle.
3. Circuitous or roundabout.
4. Referring back to itself, so as to prevent computation or comprehension; infinitely recursive.
   circular reasoning
   Your dictionary defines "brave" as "courageous", and "courageous" as "brave". That's a circular definition.
   a circular formula in a spreadsheet
   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.
5. Distributed to a large number of persons.
6. (obsolete) Perfect; complete.
   A man so absolute and circular / In all those wished-for rarities that may take / A virgin captive. 1632, Philip Massinger, Maid of Honour, act I, scene 2
7. (archaic) Adhering to a fixed circle of legends; cyclic; hence, mean; inferior.
   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?

noun

1. An advertisement, directive or notice intended for mass circulation.
2. Short for circular letter.
3. Short for circular file.
4. (dated) A sleeveless cloak cut from a circular pattern.
5. A shuttle bus with a circular route.

verb

1. To distribute circulars to or at.
   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. 1851, G. W. Muir, Report on the State of Engine and Other Furnaces, page 19
   It is true, that, to obtain these, some six hundred or more institutions were circulared, and a good many of these a second time. 1873, Old and new - Volume 8, page 101
   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. 1909, American Life Convention, Report of the Proceedings of the Annual Meeting of the American Life Convention, page 42
   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. 1962, Harrie Sheridan Baketel, Medical Economics - Volume 39, page 141
2. To extend in a circular direction.
   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. 2008, Donald E. Wagner, Kenneth Cragg, Dying in the Land of Promise, page 116