Wi-fi. W-I-F-I. Sometimes written with a hyphen, sometimes not.
Wireless fidelity. Technically, it's a standard ensuring that equipment works on a wireless network. It's on analogy with 'hi-fi', for high fidelity, that used to be common for recording some years ago.
Wifi全称为wireless fidelity.(无线保真)，从专业的角度讲，是一种确保不需要线缆也可使用因特网的技术。 Wifi和hi-fi（高保真）相似--“高保真”一词多年前就出现了，是用来形容唱片音效的。
I mean, 'wireless' was around when wireless was invented, but it was quickly replaced by 'radio'.
And everybody talks about 'radio broadcasting' not 'wireless broadcasting' and then, suddenly it came back in again with this internet connection.
说到电台的时候，人们往往用“radio broardcasing”而不是“wirelss broadcasting”，但是随着网络的出现，wireless又开始被人们使用。
It's used now for all sorts of applications.
TV remotes can be talked about as wireless, if you control your garage door, it's a wireless control, mobile phones are sometimes referred to as wireless, and GPS, you know, satellite things in your car - wireless.
Has a lot of associated terminology, of course, wi-fi is just one word of many that has come into usage in the last few years, talking about the way in which we cope with the internet.
'Hot spot' is another one, for instance, that's a location which offers a wireless connection to the internet - you sometimes see people outside houses with their laptops, where there's a hot spot, there is a connection to the internet from nearby.
例如hot spot (热点)--提供无线网络的一个地方--你有时候会看见某人拿着笔记本电脑连接附近网络的无线网点上网。
Incidentally, the opposite of 'wireless' is 'wired' - that is, using wires to carry the signal, as in, say, cable television, and that's led also to an extended use - 'wired'. 'He's wired' - that means he's alert, he's capable, he's ready.
And people who are 'wired up' are like that too! I'm wired up at the moment!
当然我可以说某人有点wired-up (兴奋)--这里又是wired的另一个用法了。我现在就有点wired-up (兴奋)。