I can guarentee you you don't have a problem with a word or letter. It's all in your head. But the best way to approach this is practice. And not focusing on that single word or letter, but just talking in general. Talk to colleges, friends, join a club where they have meetings. Discussion groups for example. Just take the pressure of that negative and focus on the good parts. That is what is going to help you advance. Most businesses have a fund pot for extra courses or improvement of their employees. Ask your boss if there is a activity (course) where you can practice your meeting skills. It helps you to improve, feel more confident and helps your boss(es) to improve their business and the image of their business. If you want to improve their business they would gladly help you to do so. I even joined a card club to make small talk. You have group of people, crowded place and zero pressure to preform. I just relaxed, played a few games and talked to strangers and had a blast doing it. That is the key. Not layering on the pressure on a single thing. Take a step back, assess the situation and approach with zero doubt.