A point that many people mentioned amid the horror and heroism of the attack at London Bridge was the enterprising use of a narwhal tusk taken from the wall of Fishmongers’ Hall to belabour the murderous knifeman.
I am surprised to find that the first person known to use narwhal in English was good old Sir Thomas Browne, in the discussion of unicorns’ horns in his Pseudodoxia Epidemica or Vulgar Erroures, where he correctly declares that ‘those long Horns preserved as pretious rarities in many places, are but the teeth of Narhwales’. Narwhal tusks are spirally grooved, and Browne observed that the long horn preserved in his day at St Denis in Paris ‘hath wreathy spires, and chocleary turnings about it’. That was in the edition of 1650. By spires he meant ‘spirals’. In the edition of 1646, the phrase was anfractuous spires. That other rhapsodic magpie, Robert Burton, had employed anfractuous two decades earlier, with its meaning of ‘spiral’ carried over from Latin. The Oxford English Dictionary helpfully provides online a little link next to the quotation from Browne illustrating anfractuous, to put it in context; but the text there supplied is from the edition of 1650, in which the word does not appear.
Anyway, narwhal itself straightforwardly refers to a kind of whale. But what does the nar- part signify? It must have Nordic origins, and some say it is from nar, ‘a corpse’, from its colour. This word had its Old English counterpart and appears in the compound orcneas, ‘walking corpses’ or ‘demon corpses’, the first element of which J.R.R. Tolkien took up as his word for evil creatures of Middle-earth. (He noted in a letter: ‘The word is as far as I am concerned actually derived from Old English orc “demon”, but only because of its phonetic suitability’.)
A persuasive alternative for the source of the first syllable of narwhal is nal, ‘needle’, referring to the sharp tusk. Other suggestions are that it is from Germanic elements that give us the now regional word nase (‘nose’) or the word narrow. Whatever the truth, we have settled into the convention of spelling the creature narwhal, while Sir Thomas Browne had the good sense to Anglicise it as narwhale.