A troglodyte is a person who lives in a cave. The word is mostly used about people in very ancient times, before history was written down — you might meet it in a book about early humans, or a museum sign about people who cut homes into soft rock. It is a bookish word; nobody uses it for a modern person who happens to live in a cave. You are actually far more likely to meet the second, joking use: calling someone a troglodyte because they act like they crawled out of a cave — rude, old-fashioned in their thinking, badly dressed, refusing to learn anything new, hiding indoors and never seeing other people. "My uncle is a complete troglodyte about the internet." This second use is an insult, but a light and slightly funny one, because the word is so long and so grand that it sounds like a joke. Said in real anger it is genuinely rude, so be careful. Also worth knowing: scientists borrow trogl- for cave animals, and there is a bird called the troglodyte (the wren) because it darts into holes. So if you meet the word in a nature book, it may be a bird, not a person.

穴居人；（引申、帶戲謔的罵法）老古板、不通人情的人。中文的「穴居人」幾乎只有字面義，罵人那層要靠上下文，台灣口語較接近「山頂洞人」（笑人跟不上時代）。