I believe any word that would exhibit negative light of either you or the folks/company you represent, it just become part of your subconscious these days. People are now self aware and clever these days. Few words hold power especially when you deal with end users/client or diverse stakeholders:
This is not important
I reckon it will be beneficial if we…
Lets not do this now
Lets park this for now and we will reiterate / come back / circle back
My favorite one:
Unfortunately
Blessing in disguise
Its not only important WHAT you said, rather HOW you say it. Being empathetic leader you become self aware in terms of what NOT to say.