It all depends on what the "common English word" is. Apple. Blackberry. Chase. Delta. EvilCorp. Fire. ... You get the idea. (I couldn't resist EvilCorp. Sorry).
Even if he was explicitly clear, there are a few points.
1) None of us are attorneys specializing in trademark law.
2) Even if there are such attorneys here, they would say "But I'm not your attorney until you retain me, so I cannot answer."
3) If the guy is just asking for a word from the description to be removed, fuck it, remove the word. He doesn't have the funds to fight it. When he has the money to pay an attorney to deal with the USPTO, Google and the opposing party, that's when he has something to work with. If it's as weak as he implies, he could potentially get the trademark invalidated and then sue for damages from lost revenue by complying (but not admitting guilt) with the initial C&D in a timely and good faith manner.
That actual trademark attorney may just say at the initial consultation, "This isn't worth my time. File form xyz yourself with the USPTO to get it invalidated, and then go back to Google with it." I've heard lawyers say that plenty of times, when there isn't enough money to be had.
They may even direct him to a group like EFF or ACLU, who would take it on principle, or even another attorney who is already defending other targets of this troll.
As not an attorney, nothing above is to be considered advice of any sort. What follows is.
Contact an attorney. Get the free or few hundred dollar consult.