A hi-fi is a set of electronic machines for playing recorded music as truly as possible — turntable, amplifier, speakers, and so on, built so the sound stays close to the real performance. That “true sound” idea is the fidelity in the full phrase high fidelity; hi-fi is just the short, friendly form.

A hi-fihi-fi is a set of electronic machines是一套電子設備 for playing recorded music as truly as possible用來盡可能真實地播放錄好的音樂——turntable, amplifier, speakers, and so on像是唱盤、擴大機、喇叭等等，built so the sound stays close to the real performance設計成讓聲音盡量貼近真實演出。That "true sound" idea這個「真實聲音」的概念 is the fidelity in the full phrase high fidelity就是完整說法high fidelity裡的fidelity；hi-fi is just the short, friendly formhi-fi只是比較簡短親切的講法

It can name the equipment (he bought a new hi-fi) or describe the sound (hi-fi speakers).

It can name the equipment它可以指設備本身（he bought a new hi-fihe bought a new hi-fi：他買了一套新的hi-fi），or describe the sound也可以用來形容聲音（hi-fi speakershi-fi speakers：hi-fi喇叭）

It had a golden age from about the 1950s to the 1970s, when people were proud of a big living-room system. Today many people just stream from a phone, so hi-fi can sound a little old-fashioned, though people who care about sound still use it with a straight face.

It had a golden age它有過一段黃金時期 from about the 1950s to the 1970s大約從1950到1970年代，when people were proud of a big living-room system那時候人們會以客廳裡一套大音響系統為傲。Today many people just stream from a phone現在很多人只是用手機串流音樂，so hi-fi can sound a little old-fashioned所以hi-fi聽起來可能有點過時，though people who care about sound still use it with a straight face不過真的講究聲音的人還是很認真在用這個詞

It is not the same as Wi-Fi, which only borrowed the shape of the name.

It is not the same as Wi-Fi它跟Wi-Fi不是同一回事，which only borrowed the shape of the nameWi-Fi只是借用了這名字的外形