What does UL mean

What does UL mean?

We always need to ensure that any device we purchase or use (for work or home usage) is UL Listed, (having the UL stamp in the back of the device), i.e., this device has been tested by an independent entity and it is safe to use.
But it is also great to know the origin of UL and what it stands for.

for download in Arabic

http://www.almohandes.org/upload/465UL Arabic.pdf

for download in English
http://www.almohandes.org/upload/17UL English.pdf