On Star Trek: The Original Series, "fascinating" is a word Mr. Spock used when confronted by something unexpected. How often did that happen in the series? More than once an episode, at least. Merriam-Webster defines the word fascinating as "extremely interesting or charming, captivating." I doubt Spock would use it to mean charming, but since the character is supposedly immune to human emotions (which wasn't quite true), we will assume he finds all things extremely interesting.
Here we have incidents that Spock found fascinating from all three seasons of the original Star Trek series, plus Star Trek: The Animated Series, the Star Trek movies, and Star Trek: The Next Generation. The use of the word is not confined to Spock, because others picked up the habit from him, too. This is another Trek supercut from John DiMarco. See some others in our previous posts. -via Geeks Are Sexy