Longman Dictionary of Contemporary English
WordNet
n. the number on the license plate that identifies the car that bears it [syn: license number]
Usage examples of "registration number".
The Army private checked her name off on a clipboard, went round to the back of the car to make a note of their registration number, returned to the window, gave Jericho's card a cursory glance, and nodded them in.
When she reached the shuttle deck, the status boards showed three private shuttles on approach, identified only by registration number.
She had never known the registration number of Ronnie's family's shuttle.
Everybody in the world's car make, colour and registration number.
Until you have told me who you are and whether you are my real uncle, and what is the registration number of your big black car, I shall refuse to answer any of your questions.