Round and round, you can make these words:
Donatist
valid
hairdo
In English the largest word you can make is woaded, which uses six of the seven letters. There are no valid seven-letter combinations from the pattern a d d e h o w.
Daydream.
centrifuge
Sized
Divots
hared, heard
The letters 'lcodu' spell CLOUD.
alodium
The longest possible word is RADIOSONDE, which is ten letters long and is a unit of measurement for weather balloons. There's no word that can be made with all of those letters.