Someone asked me this question yesterday…
What is the longest word that can be typed in (on a phone pad) by pressing each of the keys only once? (any order)
Should probably be an 8-letter word.
I have one answer, so far…
adroitly.
I am wondering if there are many others…thanks.
::bump::
Does no one have another 8-letter word that can be typed by pressing each key only once?
Come on!
Aro-
You may have a genuine stumper here. I just tried about 15 permutations of the 8 digits at phonespell and I couldn’t come up with anything other than adroitly. Of course, there are 8 factorial permutations of the digits, so I haven’t tried nearly all of them yet 
-Andrew L
A few more aredilatory, idolatry, enthalpy, unfairly, playtime. (There are several others.) If you allow QZ on 1, there’s also the 9-letter
hazelwort.
Great answer Ompha. Thanks a lot. (Glad I bumped this now!)
(BTW, my phone doesn’t have the QZ on 1, but the Q on 7 and the Z on 9)
my phone has the following letters:
2 ABC
3 DEF
4 GHI
5 JKL
6 MNO
7 PQRS
8 TUV
9 WXYZ
and, by my calculations, there are 40,320 unique 8-digit numbers which do not include 0 or 1. There are 11,664 possible ‘words’ per number, which makes a staggering 470,292,480 phone ‘words’ - well, letter combinations, really.
I can limit this slightly by removing letter combinations that do not include vowels (or Y) this means that each unique 8-digit number has 2,417 ‘words’, which makes 97,453,440 total words.
being both a programmer and slightly insane, I have spent a while creating a program that can generate these numbers, and convert them to words. my original plan was to stick these words in a word processor, and remove everything that didn’t spellcheck, thus leaving a comlpete list of all possible words. Unfortuantely it keeps crashing (probably out of memory) so we may never know …
I have, however, now got a listing of every unique (as defined in OP) 8-digit number - if anybocy would like this list, to perform their own calculations on, they are welcome to it!
Wow.
That’s quite, quite brilliant, and probably just a little bit mad too.
I never expected anyone to go so far (or to care much at all about this really). Cheers…
well, I’m just sitting here at work, being bored - sounded like an interesting programming challenge to take my off the stuff I’m meant to be programming… 
Also, you’re the only person other than me that I’ve seen who writes it ‘Norn Iron’. my dad’s from there, and I’ve always written it that way!
You’ll be delighted to know that the number to word conversion process now seems to be working, and is gradually churning out results… now I just have to find a way to eliminate the non-words!
The technique I used was basically the reverse of this. I started with a text wordlist and looked for 8-letter words containing one of (A,B,C), one of (D,E,F), etc., using awk and egrep.
A search using Lexpert reveals that there are exactly 30 eight letter words that can be spelled in this manner, of which 10-15 are ‘common’ depending on how you define that. I’ll list them all in the spoiler box below:
ADROITLY
BLOWIEST
CRYOLITE
DICOTYLS
DILATORY
ENTHALPY
EPICOTYL
FOXTAILS
GUNWALES
HAYLOFTS
IDOLATRY
INTERLAY
KEYPUNCH
KNITWEAR
KYANITES
LAUWINES
LIPOCYTE
PENALITY
PLAYTIME
SODALITY
STEAMILY
TALEYSIM
TENSIBLY
TWANGLER
TWANGLES
TWANKIES
UNEASILY
UNFAIRLY
UNFLASHY
WATERLOG