To put one over on somebody. See: con man.

Also, negative, or against. Opposite of pro.

As well, abbreviation for convict.


To begin with, the popular belief that con is just an illegal DOS name is not true. Con is the console, such as the keyboard, or in some old computers the terminal input.

There are legitimate uses for con, such as going
copy con filename.ext
This is identical to the Unix command
cat > filename
with the one difference being that the DOS con input is terminated by Ctrl-Z (or F6), and the Unix input is terminated by Ctrl-D.

Anyway, attempting to open c:\con\con or any other path:\con\con is trying to open a console inside a console. This creates an error inside the VFAT driver and the nice little Windows box blue-screens.

Not only will this work inside the Run prompt, but a link to file:///c:/con/con will also blue screen the computer when Explorer tries to open it. This creates some interesting possibilities, such as the following Java Script line:
Now, this is where the security flaws in Windows 98 come in - if an HTML-formatted email is sent to an Outlook Express client, and the above JavaScript code is either embedded in a link, or automatically loaded in the BODY tag the computer will bluescreen upon opening the email.

This bug is not present in Windows NT or Windows 2000.

Old French for female genitalia, in english, cunt. Today it is derogatory. Usage is identical to the english term.
The derogatory usage came out several centuries ago, where the term "Roi des Cons" described a regent who did not get involved in politics or managing his kingdom, but spent his days screwing his mistresses and servants.
computron = C = condition out

con n.

[from SF fandom] A science-fiction convention. Not used of other sorts of conventions, such as professional meetings. This term, unlike many others imported from SF-fan slang, is widely recognized even by hackers who aren't fans. "We'd been corresponding on the net for months, then we met face-to-face at a con."

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.

CON is the console character device under MS-DOS and related operating systems, including all forms of Windows. CON is a special, reserved file name.

What this is means is that CON behaves in some ways like a file, but isn't. In particular, data may be written to and read from CON, but CON may not be deleted, created, or renamed. Because of the semantics of character devices, all files whose base name is CON, regardless of extension, are treated identically to CON.

Because of CON's status as a console device file, all data written to it will be output to the console, which is to say the screen (unless the meaning of the console has been changed with CTTY). Attempting to read data from this file will cause data to be taken from the keyboard (same exception applies).

CON has several interesting uses. Because it behaves like a file, it can operate as either the source or destination of the COPY command. Thus, the command COPY FOO.TXT CON will display the file FOO.TXT. This is equivelent to the DOS TYPE command. However, both the above COPY command and TYPE will not display complete binary files; the former can be modified such:


The above command is the best way to display a complete binary file in DOS without any external tools. The /B flag indicates that the source is a binary file and copying should not stop at an EOF.

Another interesting use of CON with COPY is nearly the inverse: COPY CON FOO.TXT will read user input (up until EOF, or control-Z) and deposit it in the file FOO.TXT. This is a simple way to create text files (for example, CONFIG.SYS or AUTOEXEC.BAT) in an emergency situation that may preclude the use of a real editor.

CON is equivelent to /dev/console on Unix systems.

See here for more information on this subject. See also CTTY.

Con, adv. [Abbrev. from L. contra against.]

Against the affirmative side; in opposition; on the negative side; -- The antithesis of pro, and usually in connection with it. See Pro.


© Webster 1913

Con, v. t. [imp. & p. p. Conned (?); p. pr. & vb. n. Conning.] [AS. cunnan to know, be able, and (derived from this) cunnian to try, test. See Can, v. t. & i.]


To know; to understand; to acknowledge. [Obs.]

Of muses, Hobbinol, I con no skill.

They say they con to heaven the highway.


To study in order to know; to peruse; to learn; to commit to memory; to regard studiously.

Fixedly did look
Upon the muddy waters which he conned
As if he had been reading in a book.

I did not come into Parliament to con my lesson.

To con answer, to be able to answer. [Obs.] --
To con thanks, to thank; to acknowledge obligation. [Obs.] Shak.


© Webster 1913

Con, v. t. [See Cond.] (Naut.)

To conduct, or superintend the steering of (a vessel); to watch the course of (a vessel) and direct the helmsman how to steer.


© Webster 1913

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