Pixicles is a term used to describe icicle lights made from LED pixels (Pixel Icicles = Pixicles), allowing individual control of the colour of each LED.
Icicle lights are strings of drops of lights, usually hung from eaves or gutters, to give an impression of water icicles hanging from the roof.
The drops are usually of differing lengths along the string in a regular pattern; eg 3,4,5,3,4,5,3,4,5; but they can also be made using the same length drop along the length of the string; eg 7,7,7,7,7,7. Use of a regular drop can have the added advantage of using them as a matrix to display text.
Pixicles can be purchased from all the usual lighting vendors, some who will custom make the length of strings and drop pattern desired.
There are also available from several vendors, or you can manufacture your own, ABS or Coro pixicle holders that will aid in keeping the drops of lights hanging neatly down.