The idea you keep to yourself in the meeting helps nobody, including you.

An unspoken idea has exactly the same effect on the room as no idea. You get none of the credit, the group gets none of the benefit, and the whole thing is usually settled in the two seconds you spend calculating whether it sounds stupid. Most of the time it does not, and half the room was thinking something similar.

Set yourself a rule for the next meeting or class: say one thing, even if it is a question. Prepare it beforehand if that helps. The bar is speaking, not being right.