Word To Use Today: yotta.

 Okay, yotta isn't actually a word, it's a prefix (that is, a letter or group of letters stuck onto the front of a word to change its meaning).

Yotta- is, literally, the greatest prefix in the world - and that's official, because it's a number thing, like kilo- (which means a thousand times) or giga- (a billion) or tera- (a trillion).

Now, you may smirk wisely and say, ah, but it begins with a Y, so the prefix beginning with a Z will be even bigger once someone's invented it.

But there you'd be wrong, because the one beginning with a z, zetta, is a thousand times smaller than yotta- (and the other one beginning with a z, zepto, is as much smaller than one than as a zetta is greater than it).

These scientists, eh? Either they don't know their alphabet, or they just don't have logical minds.

Anyway, yotta-. It's big. I mean, really big. You thought the observable universe was big? It's less than a yottakilometre across.

The mass of the Earth is a bit less than six yottakilograms.

If you want to write down the number associated with yotta- then you need a figure one followed by twenty-four zeros. Or, if you like, you can just use the symbol Y.

There are yottabytes in computing, but the best unit has to be the yottawatt. 

Yes, the yottawatt.

The output of the sun is 385 yottawatts.

Could anyone possibly resist spreading this news immediately?

I don't think I can.

Prefix To Use Today: yotta-. This comes from a word for eight. That's because this number, written a different way, is a thousand to the power of eight. The Italian word for eight is otto and the Greek is okto.

Yotta- became an SI unit prefix in 1991.

Yocto- implies a number as much smaller than one as yotto- is greater than it.