hairdo
hared, heard
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.
forehead
cedar + h + d = cheddar
Words that can be made with the letters I I D N V H S E are:dendiedindinediveendhehenhihidhidehiehindhivehisIidinissidesinsine
homestead
chados
redhead
knithreaded
The longest word you can make out of those letters is "hydromagnetry," which has 13 letters.
A seven letter word is hurdles.
Using all the letters in one word, Nothing.