Diffusion (noun). the act of diffusing, or the state of being diffused; a spreading; extension; dissemination; circulation; dispersion. Diffusion (noun). the act of passing by osmosis through animal membranes, as in the distribution of poisons, gases, etc., through the body.
Learner's definition of EXCITEMENT. 1. [noncount] : a feeling of eager enthusiasm and interest : the state of being excited. Our excitement was building/growing/mounting as the end of the game approached. His hands shook with excitement. The child cried out in excitement.
If you're excited you're enthusiastic and animated, like a kid in a candy store. Or a kid on Christmas morning. Or a kid on the last day of school. Meaning more than just wildly happy, excited describes all sorts of excessive emotions (and not always the good ones). If you're excited you might be agitated, nervous, anxious, or worked up about something.