A British journalist wrote the phrase in a review in 1984, an American band had already used the word in a song title, and neither of them was trying to name anything. That is the whole story, and like most naming stories in popular music it is considerably less deliberate than the tidy version suggests.
What is worth understanding is why this particular word stuck when several others were in circulation, because the answer says something real about what the music actually is.
The word before the genre

Thrash was already in use in punk and hardcore before anybody applied it to metal. It described fast, short, aggressive songs and the physical way people moved to them, and it carried an implication of flailing rather than of precision.
Anthrax put "Metal Thrashing Mad" on Fistful of Metal in January 1984, using the word as a description of what the audience did rather than of what the band played. Within about eighteen months it had become the name of the genre, which cannot have been the intention.
Malcolm Dome and the review
The usual attribution is to Malcolm Dome, writing in Kerrang!, who used the phrase thrash metal in print in 1984 in connection with that Anthrax song. Dome himself spent the rest of his life saying, with some amusement, that he had not coined a genre and had simply reached for an adjective.
Whether he was strictly first is genuinely uncertain. Fanzines were using similar language at the same time and nobody was keeping records. What is not uncertain is that Kerrang! had the circulation to make a phrase stick, and the British press was where this music was being taken seriously several years before the American press caught up.
What else it was nearly called
Several alternatives were in play between 1983 and 1986 and each of them failed for a specific reason.
Speed metal was the leading candidate and it was already taken, or at least contested, by a European strain that emphasised melody, clean singing and virtuosity rather than aggression.

Power metal, absurdly, was used for a while to describe some of these bands, before the term migrated to something almost opposite. Black metal was taken in 1982 by Venom for a record that was not black metal either. And hardcore metal was used occasionally and never caught on because it implied a subordinate relationship to punk that the metal audience would not accept.
| Term | Used for | Why it did not stick |
|---|---|---|
| Speed metal | Fast metal generally | Claimed by the melodic European strain |
| Power metal | Briefly, these bands | Migrated to almost the opposite music |
| Black metal | Venom and imitators | Reclaimed by Norway from 1991 |
| Hardcore metal | The crossover bands | Implied punk was the senior partner |
| Thrash metal | The American and German bands | Stuck, because it described the audience |
Why this word won
Because it describes the effect rather than the technique, and effect is what an audience can actually name.
Speed metal describes a measurement. Power metal describes an ambition. Thrash describes what a room full of people does when the music starts, and it carries the right implication of violence without control. A teenager in 1985 did not need the word explained.
It also has the advantage of being slightly rude. The genre was made by people who were not interested in being respectable, and a name that sounds like an insult suited it better than anything a record company would have chosen. Every attempt to impose a more dignified label failed, which is exactly what should have happened.
Where the speed came from in the first place is dealt with in Motorhead and the Speed, and the period that produced all of it is covered in the chapter above.
What the bands called themselves
Mostly nothing, and that is worth remembering when the naming argument gets heated.
Musicians in 1983 and 1984 described what they did as metal, or as heavy metal, or as fast, and the genre labels were applied from outside by journalists and record shops who needed somewhere to file things. Several of the founding bands actively disliked the word when it arrived: it sounded to them like a description of the crowd rather than of the music, and there was a suspicion that it belonged to punk.
That resistance faded within about two years for the usual commercial reason. Once shops had a section and magazines had a heading, being inside the category was worth more than the objection to it, and by 1986 the bands were using the word themselves.
How the label hardened
The mechanism by which a loose adjective becomes a genre name is always the same and it is worth spelling out.
First the press uses it as a descriptor. Then a record shop uses it as a divider in a rack. Then a compilation appears with the word on the cover. Then a band puts it in a song title, which happened here in both directions and slightly out of order. And finally a distributor uses it in a sales category, at which point it is no longer a description of anything, it is an address.
By 1987 thrash metal was an address. It told a buyer which rack to walk to and a promoter which bands would draw the same crowd, and its usefulness as a description of what a band actually played had already started to slip. That is why arguments about whether a given group counts are usually pointless: the word stopped being a technical term almost as soon as it stopped being an insult.
The words that came afterwards
Everything downstream of this genre was named the same way, by outsiders reaching for an adjective, and the pattern is worth noticing because it never changes.
Death metal came from a Possessed song title and a Chuck Schuldiner band name. Black metal came from a Venom album sleeve, and the music now called that has almost nothing to do with the record. Crossover came from a D.R.I. album cover. Grindcore was coined by a teenager in Birmingham. Not one of these was a considered decision by anybody with authority.
What that tells you is that genre names are not descriptions, they are handles, and they get attached by whoever needs to point at something first. The music itself is indifferent to what it is called, which is why every argument about whether a particular band counts as thrash is really an argument about shelving.
Sources and notes
The attribution to Malcolm Dome follows his own repeated public account and the contemporary Kerrang! record. Fistful of Metal was released in January 1984. Priority claims for the phrase in fanzines of the same period cannot be verified.