A joist is one of the long beams that lie across a building to hold up a floor, or to hold a ceiling from above. When the house is finished you usually cannot see them: they hide under the floorboards or above the ceiling.

A joist is one of the long beamsjoist是其中一種長長的梁 that lie across a building橫跨建築物架設， to hold up a floor, or to hold a ceiling from above用來撐起地板，或從上方撐住天花板。When the house is finished房子蓋好之後， you usually cannot see them你通常看不到它們：they hide under the floorboards or above the ceiling它們藏在地板下面，或天花板上面。

Builders set many joists side by side, like ribs, then lay the floor on top. They may be wood or steel.

Builders set many joists side by side工人會把很多根joist並排架好， like ribs就像肋骨一樣， then lay the floor on top然後把地板鋪在上面。They may be wood or steel它們可能是木頭或鋼材。

Ordinary people often just say beam, and that is close — though actually a joist is a particular kind of beam. It is not the one huge beam that runs the long way through a room. It is one of the many smaller ones that run across, carrying the floor or ceiling.

Ordinary people often just say beam一般人常常就直接說beam（梁）， and that is close這樣講也算接近— though actually a joist is a particular kind of beam不過其實joist是梁的一種特定類型。It is not the one huge beam that runs the long way through a room它不是那根貫穿整個房間、長邊方向的大梁。It is one of the many smaller ones that run across它是很多根橫向架設的小梁的其中一根， carrying the floor or ceiling負責撐起地板或天花板。

Builders, architects, and people doing repairs use the word. A beam you can see in a barn roof is more often a rafter or just a beam; joists are the hidden floor-and-ceiling ones, unless someone leaves them showing on purpose as a look.

Builders, architects, and people doing repairs use the word工人、建築師，還有做修繕的人會用這個字。A beam you can see in a barn roof你在穀倉屋頂看得到的梁 is more often a rafter or just a beam比較常是rafter（椽木）或就叫beam；joists are the hidden floor-and-ceiling onesjoist是那種藏起來、撐地板或天花板的梁， unless someone leaves them showing on purpose as a look除非有人故意把它們露出來當作一種造型。

There is a rare verb to joist, meaning to fit a floor with joists, but you will almost always meet the noun.

There is a rare verb to joist有一個很少見的動詞to joist， meaning to fit a floor with joists意思是幫地板裝上joist， but you will almost always meet the noun但你幾乎都只會遇到名詞用法。