Do you mean a 2 way or a 3 way adapter, or an extension lead? Both will allow you to connect 3 or more appliances to one socket.

We say a power board, a double adaptor or an extension cord.

Any of these names: power strip power board extension block For these look here: http://images.yourdictionary.com/power-strip 2-way adapter http://www.google.com/imgres?hl=en&sa=X&biw=1440&bih=799&tbm=isch&prmd=imvns&tbnid=dhY1Glb8BhcS5M:&imgrefurl=http://www.spyguy.co.uk/2-way-Adapter-Recorder/76.htm&docid=blISkshhpmUTxM&imgurl=http://www.spyguy.co.uk/photos/1.709988adaprec_1.jpg&w=300&h=268&ei=vFzNTuSdO4nR4QTrn61f&zoom=1 or 3-way adapter http://www.google.com/products/catalog?pq=3%5C-way+electrical+adapter+images&hl=en&ds=pr&cp=24&gs_id=49&xhr=t&q=3%5C-way+electrical+outlet&tok=oUeIGYvaJTATDv0PUwS2ZQ&gs_upl=&bav=on.2,or.r_gc.r_pw.r_cp.,cf.osb&biw=1440&bih=799&um=1&ie=UTF-8&tbm=shop&cid=274632181563811200&sa=X&ei=hlvNTqLVGe7c4QS22Pg5&sqi=2&ved=0CJABEPICMAE

A powerboard?

Are you sure you need electronics to do that ? I think you only need 'wiring' as Padraig told, and keep an eye on the total power surging from the device in order to prevent overheating and possibly fire.