Given your reluctance to confront your boss, I advise first setting a good example in any upcoming meetings where he's present by noticeably crediting someone for an idea, thereby showing him how it's done. If he doesn't take the hint and his behavior continues, I suggest you compile two or three solid examples of this conduct. Then, meet with your boss privately and ask why he dismissed these ideas only to later present them himself in public forums. Perhaps give him an out by implying he may not be aware of what he's doing, but that it is nonetheless demotivating.

Your boss will either respond by changing his behavior or continuing on with it. If he changes course, you'll be able to discuss topics with him without worry. If he persists, your subsequent step should be to starve the beast, so to speak. That means not giving your boss too much information about any idea. You might want to only share part of a concept with him until you can share all of it later with the larger group, thus making sure that the credit goes where the credit is due.E