Short for very important person: someone famous, powerful, or rich enough that a place gives them special treatment — a separate entrance, better seats, a private room, someone to look after them. The word is really about the treatment as much as the person. A VIP is whoever this particular place has decided to treat well tonight. It works as a noun ("a VIP", "a room full of VIPs") and, very commonly, in front of another noun: VIP lounge, VIP ticket, VIP room, VIP table, VIP service. That second use is everywhere in advertising, and it has stretched a long way from "important person" — plenty of VIP tickets are simply the ones that cost more. Anyone can buy one. So the word often means "the expensive version" now, not "the famous guest." Say the letters one by one: V-I-P. The plural is VIPs, no apostrophe. You can also use it lightly as a joke about a friend — "make way, VIP coming through" — and that teasing use is common in speech.

貴賓、大人物；VIP。台灣直接講 VIP 就好，中文書面才寫「貴賓」。注意台灣的 VIP 常常只是「付比較多錢的方案」(VIP 包廂、VIP 會員)，不一定真的是名人。