‘Why are you filming this?’

‘For everyone’s safety.’

Those are the last words in a 46-second video that was watched by more than three million people on YouTube last week. The question was asked of the unseen cameraman by a black woman who had been haranguing a white youth at San Francisco State University for wearing dreadlocks (or the best he could manage with his weedy hair).

I’ve written about being safe in universities before, but this incident focused on cultural appropriation, which is a new crime discovered by people who think it in fact misappropriation to adopt the cultural expression of another ethnic group. Search me.

Of course the wearing of dreadlocks has a meaning, even if few can agree on it. The haranguee, one Cory Goldstein, went on about Egyptians, ancient ones presumably. Lord Scarman once insisted that Rastafarians were inspired by Masai warriors. Today, dreadlocks are the must-have accessory. In South Africa people wearing them are mugged in Johannesburg by dreaded dread thieves with knives and scissors, who sell the locks to hairdressers who weave them on to eager customers’ bonces.

But what does the word dreadlocks mean? The Oxford English Dictionary, not immediately helpfully, quotes the two-word Natty Dread, the name of a song by Bob Marley from 1974 . The lyrics go: ‘Dread, Natty Dread now, (Natty Dread)/ Dreadlock Congo Bongo I. (Natty Dread)/ Natty Dreadlock in a Babylon: (Natty Dread)/ A dreadlock Congo Bongo I.’

Obviously dreadlock refers to hair. Natty dread has been interpreted by some as natural dread — hair untouched by the wicked Babylonish triad of razor, scissors and comb. In reality natty is the word knotty. But later in the song, Mr Marley says: ‘I talk to some Dread on fourth street.’ Here, dread means ‘dreadlocked people’. The term has been used contemptuously by outsiders, but for Rastafarians it has been a badge of those who fear the Lord. (The Anglo-Saxons had a word ofdread, ‘to terrify’.) Rastafarians would agree with Milton, who wrote of shorn Samson, mocked by the Philistines ‘Shouting to behold their once great dread, captive, and blind before them.’