“Sydney braces for surge in wildfires” said a headline on the BBC Online site earlier this week about the fires raging in New South Wales. That was an odd-sounding choice of word, so far has wildfire moved — particularly in Britain and Australia — from a literal reference to a raging conflagration to a metaphorical word for something that moves fast. Australians don’t use the term at all — they call them bushfires. Only in the US is it still used for a real fire.
According to the big Oxford English Dictionary, the sense of a fast-moving blaze burning out of control died out in Britain in the seventeenth century; it isn’t in the New Oxford Dictionary of English in that sense at all. The original meaning — sometime in the twelfth century — was of a fire that had been caused by lightning (and so a doubly inappropriate word for these current Australian outbreaks, many of which are alleged to have been deliberately started). It was a fire that occurred in the wild, the uncultivated countryside, not necessarily one that was untameable (though the association of ideas between these two senses must have been hugely powerful).
Somehow this idea got tangled up in people’s mind with the Jack-o’-lantern, will-o’-the-wisp, friar’s lantern, or ignis fatuus, that mysterious, cool, dancing flame of burning methane sometimes to be seen in marshes. The word wildfire comes from the old Germanic wildfeuer for that phenomenon (modern German prefers Irrlicht or Trugbild).
In the thirteenth century, the same word became the usual English way to speak about the invention otherwise called Greek fire — a mixture of inflammable substances that was a precursor to napalm — easy to light but as hard to put out as any bushfire. The link with lightning resurfaced at the end of the seventeenth century, when the word was used for that curious phenomenon in which lightning flashes but no thunder is heard, better known as summer lightning.
But our current sense of wildfire, for something that moves as fast as a fire in dry country, seems to be owed to Shakespeare, who used it in The Rape of Lucrece for an enchanting storyteller “Whose words like wildfire burnt the shining glory / Of rich-built Ilion”. So far had the figurative sense taken over that by the end of the seventeenth century William Dampier could write in his New Voyage round the World of 1699, quite without any punning intention, that they set fire to some grassland, which burnt “like Wild-fire”. How else?