U factor is a rating of a material and its ability to transfer heat (lower number = less heat transfer)

Uniformity is theoverall consistency of the appearance of a paint coat

A union is a special straight line fitting used to connect and seal two ends of a pipe or tube. The multi-threaded connection allows for future disassembly 

To unload is the process of paint transfer from a properly loaded brush or roller to the target surface before distribution and finish

Urethane is a paint created by mixing pigment with polyurethanes. This paint type is good for exterior use and can be applied over oil-based enamels.

A utility knife is a retractable general-purpose razor cutting tool

UV or Ultraviolet radiation is a type of electromagnetic radiation that is not visible to the eye but makes up 10% of sunlight. UV radiation is known for its ability to degrade and discolor materials over time