A tilde sign (~) is sometimes used in logic
to denote the boolean
, causing no end of pointless confusion when people assume it is being used in one of its other senses - 'roughly', or 'is approximately equal to'. Other, less ambiguous but slightly more obscure symbols for 'is approximately equal to' include an equals
sign (=) with a tilde replacing the top line, or placed above the top line (≅), or with both lines replaced by tildes. In case you really want to make sure that most of your audience has to look it up, the same relation can also be represented by a line shaped like a bell curve
over another line, or by an equals sign with dots outside it at the top left and bottom right corners.
Tildes are often used in web addresses - usually this is because they have been imposed from on high, presumably in order to prevent them from being too easy to remember and to say out loud; in this capacity a tilde is usually referred to as a little squiggly line or similar, because most people haven't the faintest clue what they are supposed to be called. It is hard to imagine anyone using '~' in their own web address by choice, other than the sort of people who don't see anything wrong with choosing names like g5v3fe6g. Note that under certain circumstances a tilde appearing in a web address will get mangled to '%7E'. If you can't find a tilde on a keyboard - they do move around rather a lot - you could always try replacing it with this.
In the Other Users nodelet, a tilde appears next to the names of users in rooms other than the main one. These are effectively pipelinked to the room in question, so if you want to see which one it is just hover the mouse cursor over the tilde to see its name.