Longest Word using different letters

[Marc Meakin]

What is the longest word in the dictionary that uses a letter only once?
I know of a 15 letter word.
Edit turns out my word is only in CSW.

[Dinos Sfyris]

Is itUNCOPYRIGHTABLE?

[Peter Mabey]

Is itUNCOPYRIGHTABLE?

Could that be pluralised?
DERMATOGLYPHICS is valid

[Marc Meakin]

Is itUNCOPYRIGHTABLE?

Yes, although Peter's one is valid on Lexplorer.

[James Robinson]

Is itUNCOPYRIGHTABLE?

Yes, although Peter's one is valid on Lexplorer.

Both the answers were mentioned in QI, Series C, Episode 3 a few years ago as the longest words without repetitive letters.

[Gavin Chipper]

Is itUNCOPYRIGHTABLE?

Unfortunately not, so the answer can't be printed here.

[Peter Mabey]

I'd like to buy a small water feature in Devon, so I could show people MY BUCKFASTLEIGH POND

[Kirk Bevins]

I'd like to buy a small water feature in Devon, so I could show people MY BUCKFASTLEIGH POND

Sadly all the ponds have gone in Devon, only fountains remain. Shame.

[Marc Meakin]

Peter Mabey said: MY BUCKFASTLEIGH POND
Is that the longest sentence using different letters?

[David Roe]

A contrived newspaper headline about the failed theft of a large block of stone from a Welsh valley read:

Quartz Glyph Job Vex'd Cwm Finks

which is probably just about as good an attempt at a 26-letter sentence as possible.

The longest placename in the UK that I know of is Bricklehampton, Worcestershire. 14 letters.

[Dmitry Goretsky]

There are 26 letters in English, so the longest word using different letters can have no more than 26 letters. Your task is to find the longest word using 26 different letters, then 25, and so on.

[Kirk Bevins]

There are 26 letters in English, so the longest word using different letters can have no more than 26 letters. Your task is to find the longest word using 26 different letters, then 25, and so on.

Er what the fuck?

[Marc Meakin]

There are 26 letters in English, so the longest word using different letters can have no more than 26 letters. Your task is to find the longest word using 26 different letters, then 25, and so on.

Er what the fuck?

Is Dmitry Goretsky related to Jason Larson?

[Joseph Krol]

I believe the name for the type of word you seek is an isogram. Wikipedia provides a rather long list. The longest I can find are:
For 17:
subdermatoglyphic
For 16:
uncopyrightables
For 15:
misconjugatedly, uncopyrightable, dermatoglyphics, hydropneumatics

[Rhys Benjamin]

14:

ambidextrously

[Gavin Chipper]

1:

Partridge in a peartree