HW

HW stands for:

Citroën Type H, model name
Polish license plate for border protection
Hardware, a general term for mechanical and electronic equipment of a system, such as a computer system
Hello ( airline), a former Swiss airline ( IATA code )
Flood
Northing or height value
Hot Wheels Model Cars by Mattel
Tungsten carbide, abbreviation according to ISO 513

HW as distinguishing signs on license plate:

404205