‘Onboard’ or ‘On Board’: What's the Difference Between the Two?

Carly Forsaith,
updated on
December 23, 2022

‘Onboard’ or ‘on board’ look very similar; the only difference is the space between the two. So what’s the difference? And when should you use which? We’ll cover all that in this article.

In short, ‘onboard’ is an adjective and a verb, and ‘on board’ is a prepositional phrase. So when to use it will depend on what you’re trying to say.

What is the Difference Between ‘Onboard’ or ‘On Board?’

Though they look very similar, ‘onboard’ and ‘on board’ do not mean the same thing. That slight difference - a space between the two words - changes everything.

‘Onboard’ as one word can be used as an adjective or a verb, depending on the context. As an adjective, it describes an item that is on a vessel, like a ship or an airplane. As a verb, it’s the process of initiating someone in a new role, usually a job.

‘On board’ is a prepositional phrase. You can use it to express either being physically on board a vessel or metaphorically on board with a plan or project.

When to Use ‘Onboard’

Let’s go into a little more depth with the two different ways you can use the word ‘onboard.’ We’ll start with the adjective. An adjective qualifies as a noun. Therefore, you can take any noun and add ‘onboard’ to it to signify that it is on a vessel. Here are some examples:

The onboard entertainment is here to help make your flight more enjoyable.

Local buses are now equipped with onboard USB chargers.

They offer several vegan options for their onboard meals.

Top Tip! Sometimes the adjective is spelled with a hyphen, like such: ‘on-board.’

As I mentioned earlier, ‘onboard’ can also be a verb, and it describes the process of helping new employees get the hang of their job role through a series of training, orientation, or talks.

On Friday, we’ll use half of the day to onboard the new employees.

Since the role is remote, the onboarding process will take place over Zoom.

Have the new employees been fully onboarded?

When to Use ‘On Board’

‘On board’ in two words is a prepositional phrase. The word ‘on’ is a preposition to signify your location. That’s why you use this phrase to talk about a thing or person located on a vessel. For example:

All the passengers are on board; the plane can now take off.

There’s a pool on board.

He was one of the musicians on board the Titanic.

That said, you can also use it metaphorically to say that someone agrees with or supports a plan or idea. For example:

We need the whole organization on board with the plan.

It would be good to have you on board to help set up the project.

That sounds like a fantastic idea - I’m on board!

Concluding Thoughts for ‘Onboard’ or ‘On Board’

So there you have it. The difference between these two words is in how you use them. Does the context call for an adjective or verb? Use ‘onboard.’ If the context calls for a preposition, use ‘on board.’

If you’d like to learn to master the difference between more similar words, head to our blog, where we cover many other commonly confused words in the English language.

Written By:
Carly Forsaith
Carly Forsaith is one of the lead freelance writers for WritingTips.org. Carly is a copywriter who has been writing about the English language for over 3 years. Before that, she was a teacher in Thailand, helping people learn English as a second language. She is a total grammar nerd and spends her time spotting language errors on signs and on the internet.

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