What is the definition of Primarily Fear?

"Primarily fear is like the silent alarm clock in your brain, but instead of waking you up for a workout, it makes you jump out of bed at the slightest hint of something lurking in the shadows. Imagine it this way: 'Primarily fear, the silent alarm that makes you think, 'Oh no, did I just step on a ghost's tail?'"

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Here's an edgy sentence using that definition: "The only thing more terrifying than the approaching storm was my own primary fear of being chased by a giant, fear-obsessed squirrel."