Onboard vs. on board

Onboard is one word (sometimes hyphenatedon-board) when it comes before the noun it modifies (e.g., onboard radio, onboard computer). Elsewhere, writers usually make on board two words. For instance, one might write, “We brought a radio on board so we could have an onboard radio.”

If it helps, think of it this way: the two-word on board usually means the same as aboard, and aboard would usually work in its place. Aboard would not make sense as a replacement for onboard. Try it with the examples below.



Justin boasts an onboard 3-D camera system for analyzing points in space. [Wired News]

Although the airline grabs headlines for threatening to charge people to use onboard toilets or save money by dumping co-pilots, it normally turns to conventional ruses. [Guardian]

At one highway fill-up, the onboard computer showed I had a range of 880 km. [National Post]

On board

President John F. Kennedy called Shepard after he was taken on board the aircraft carrier that retrieved him from the ocean. [USA Today]

San Pietro was being sailed by the remaining crew on board. [Stuff.co.nz]

10 thoughts on “Onboard vs. on board”

  1. What about in case of: “We are going to onboard 20 new employees next week?” Which way would be correct then? Hyphenated?

  2. Good explanation. So is it:
    “The technician wanted to abort coming aboard the boat to fix the on(-)board radio because of the bored members on board?”

  3. This was really useful, thanks. I prefer to use the word ‘aboard’ instead of two words. However, what about when talking about people on board? Could I then use ‘aboard’ or is it onboard?

  4. Boy, I don’t know. This used to always be used in the one-word form years ago, I believe. I can maybe see it as two words when referring to someone coming onto a boat or ship, but that’s about it. However, a lot of the rules have changed over the years, most of which I don’t agree with.

  5. What about when used by Human Resources staff to refer to orienting new employees into the company: “Our onboarding process begins before the new hire’s first day and can last as long as a year.”


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