Going down .

[swannbaker]

Take an English word of 9 different letters . Remove the 4th and 7th letters , leaving the order unchanged , to produce a 7 lettered English word . Now take the 7 lettered word and again remove the 4th and 7th letters and leave the order of the remaining letters unchanged to produce a 5 lettered English word . All 3 words mean , more or less , the same thing . What is the 9 lettered word ?

[pquinlan]

I have a word that's similar but different. CLEANSERS, remove two Ss for CLEANER, Remove ER for CLEAN. Doesn't meet your condition of 9 different letters anyway. Interesting puzzle.

[swannbaker]

Good try pq . The answer is frangible .