Stock that was never sold and never used — it sat in a shop or a warehouse until the model was discontinued, and it is still in that state.
Common with sneakers, where it usually means never worn, with the original box. Also used for clothing, watch parts, and anything with a production run.
What it does not promise
Not perfect. Ten years in a stockroom does things: boxes dent, labels yellow, and on trainers the midsole can crumble whether or not anyone wore them. Deadstock describes history, not condition.
Not rare. Plenty of deadstock is unsold because nobody wanted it.
Not authenticated. The word says nothing about whether the thing is genuine. Metzee's position on counterfeits
The words that travel with it
DS — deadstock. VNDS, "very near deadstock" — worn once or twice, honest shorthand on sneakers. NIB / BNIB — new in box, boxed but not necessarily old. NOS, "new old stock" — the same idea outside sneakers, common in watch and car parts.
None of these is a Metzee term; they are collector shorthand, and a seller is free to use them. Condition words across every category
The one question to ask
"How has it been stored?"
For anything with glue, foam or rubber in it, storage matters more than whether it was worn. A box kept in a dry cupboard and a box kept in a damp garage produce very different objects from the same word.
A good seller answers this specifically. A seller who will not is telling you something.
What to look at in the show
Ask them to flex the sole, on trainers. Crumbling shows immediately and photographs badly.
Ask for the inside of the box and the label. On old stock the label is the dating evidence.
Ask about smell. Not a joke — long storage is the commonest reason a deadstock item comes back.
Live video is unusually good for this, which is the argument for buying this kind of thing in a show rather than from photographs. How a live auction show works
For sellers
Use the word if it is true, and then say the condition separately. "Deadstock, never worn, but the midsole has yellowed and the box is crushed on one corner" sells better than "deadstock" alone — because the buyer who would have returned it never bids, and the one who bids is happy. How to write a condition description
More: what do NM, VG and the rest mean, condition words, how to describe condition.