A negawatt is a way of talking about energy you did not use. If a machine is smarter, or you switch something off, the electricity you save can be counted as if it were power you had 'made' by not wasting it. One negawatt is, in that playful measuring, one watt of power saved. The word was coined by Amory Lovins, who works on energy, as a squeeze of 'negative watt', built to sound like megawatt. He said it began as a typo: someone wrote megawatt wrong in a Colorado utilities paper. It is not an official international unit you will find next to metre and kilogram; people who plan energy use it as a sharp joke that became a real idea. Saving a megawatt of demand can be as useful as building a megawatt of new supply. Though actually, you cannot hold a negawatt in your hand — it is a saved watt, not a thing in a wire.

負瓦（因省電而少用掉的電量；能源政策用語，不是正式國際單位）