The boards in Words with Friends and Scrabble have 15 spaces tall and wide. But, that does not mean you can play any 15 letter words.
To create 15 letter words they have to be broken up into separate words because you only get 7 tiles at a time. Plus, you are limited to how many tiles are available in the tile bag.
So to simplify this process, here is a list of 10 of the longest words you can make:
Troubleshooting
Trouble, shoot, shoo, and ting are all valid words. So, start by building the word shooting with either shoo and ting or shoot and "ing." Then you can add trouble in the beginning to finish it.
trouble - shoo - ting
Up to 122 points
Personification
Person and cation are both valid. So, build those on each side and use "ifi" to connect them.
person - ifi - cation
Up to 52 points
Interdependence
Inter, depend, and interdepend are all valid. So, start by building interdepend and add "ence" at the end.
inter - depend - ence
Up to 84 points
Acknowledgeable
Know, ledge, knowledge, acknowledge, and knowledgeable are all valid. So, you can start by making knowledge, then adding either "ack" to the beginning or "able" to the end. Then, add the other one that wasn't used afterward.
ac - know - ledge - able
Up to 324 points
Notwithstanding
Not, with, stand, ding, standing, and withstanding are all valid. So, you can start building by using either ding or with. Then you can finish making withstanding to be able to add not in the beginning.
not - with - standing
Up to 78 points
Trustworthiness
Trust and worth are both valid but "trustworth" is not. So, first, build worthiness then add on trust to the beginning.
trust - worth - iness
Up to 72 points
Foresightedness
Fore, sight, ed, ness, foresight, and foresighted are all valid words. So, start by making foresighted using a combination of those words then add ness at the end.
fore - sight - ed - ness
Up to 84 points
Transparentness
Trans, parent, ness, and transparent, are all valid words. So, build transparent then add ness at the end.
trans - parent - ness
Up to 75 points
Semitranslucent
Semi, trans, lucent, and translucent are all valid words. So, start by building translucent then add semi in the beginning.
semi - trans - lucent
Up to 81 points
Interchangeable
Inter, change, able, interchange, and changeable are all valid. This is one of the easiest words you could make because it is very interchangeable.. I had to sorry. You can start with inter, change, or able. Then, you can add the others as you go.
inter - change - able
Up to 90 points
All of these words will work in Words with Friends or Scrabble. But even though it's possible, it would be very difficult to have all the letters and set up all the words in the right place. Nevertheless, it would be fun to try and play one of these words in a game and rack up some major points.