You can think of bogey as the shape in the dark that you cannot name. Not a described monster with teeth and a colour — just something there, and the fact that you cannot see it well enough to say what it is. That gap is where all the fear sits, which is why the same word can move so easily out of children's stories. Give the gap to a worried adult and it becomes the thing hanging over the whole year. Give it to someone watching a radar screen and it becomes the dot with no name on it. Turn the light on, ask for the call sign, put the real numbers up — and in every case the bogey stops being one.
From the word’s history
The packet's Wiktionary etymology says the origin is uncertain: probably related to bogle, or an alteration of Middle English bugge, a frightening spectre or scarecrow, with possible Welsh and Germanic connections. The source itself says uncertain, so this is a clue rather than a settled fact.
本批資料附的 Wiktionary 詞源說這個字來歷不確定：可能跟 bogle 有關，也可能是中古英文 bugge「嚇人的鬼影、稻草人」的變體，另外還提到威爾斯語和日耳曼語的可能性。資料本身就寫 uncertain，所以這裡只當線索看，不當定論。值得注意的是，它列出來的每一個可能來源都在講「嚇人的東西」，跟現在的核心畫面是同一個方向。
Wiktionary etymology text supplied in this packet (source_ref kaikki:3f6f69a190036ae4:494884570); the source explicitly marks the origin as uncertain
登入就可以看每一支怎麼連回核心畫面。