Today, I was talking to my friend. She is very good at English. During this conversation, she said, "I am on THE bus". I think, she has misused the definite article. In my opinion, it should have been, "I am on A bus". Because this is the first time she said anything about this bus. On the other hand, I know that she generally travel by bus.

  • Where I live (north of UK), it's common to say "I'm on 't bus'. Where 't is a contraction of "the". This could be pronounced (Yorkshire folk pronounce 't as "tuh"), but some would even miss that out and put a stopping sound on "on" to almost make it "on'd" as in "I'm on'd bus". (Oh, and in Oldham bus is pronounced buzz).
    – Neil
    Commented Jul 14, 2017 at 11:51
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    You don't tell us whether you were also on the bus, or whether this was a phone conversation. That information is important here. Commented Jul 14, 2017 at 18:28
  • @P.E.Dant - This was a phone conversation. Commented Jul 15, 2017 at 11:43
  • Our use of the definite article is extremely nuanced and complex. When I proof-read my friend's writing (a fluent, but non-native, speaker), I invariably remove every 'the' they include, and insert every one they omit - to their eternal frustration.
    – Strawberry
    Commented Jul 15, 2017 at 23:02
  • According to what I have understood, “I am on the bus” is ONLY ACCEPTED because it is a fixed expression just like “I am on the phone”, right? Suppose my friend were on her motorbike, then it would have been wrong for her to say, “I am on the motorbike”. Did I get it correct? Commented Jul 16, 2017 at 5:27

5 Answers 5


You wouldn't normally say on a bus; on the bus is a fixed expression.

The reason why the is used in that phrase is probably because the bus here is something we all know about, something that by extension refers to the institution that represents the (public) transport bus service that uses buses to drive people around the city. The phrase doesn't refer to any bus in particular per se.

In his book, Practical English Usage (69.5), M. Swan says the following:

We use the (with a singular countable noun) when we talk about some kinds of thing that are part of everybody's lives, like ‘the bus’ or ‘the hairdresser’. In this case the bus, for example, does not mean ‘one bus that you know about’; we use the to suggest that taking a bus is a common experience that we all share.

To address the comment and some additional questions one might have after reading the above:

I merely wanted to answer the question of whether on the bus is grammatical in that context, and how that's accomplished – not suggest that on a bus isn't. It would be more usual, given the context the asker provided, for their friend to say I'm on the bus and not I'm on a bus.

I'm on the bus might mean "I'm on the bus I tell you I'm on every day – my school bus", i.e., "...the bus you expect me to be on at this time". It could also mean "I'm on the bus we previously discussed". Et cetera.

Can you say on a bus? Yes, you can say, for example,

I can't talk to you right now, I'm on a bus.

As you said, this introduces a bus; you're talking about it for the first time and identifying the vehicle as a bus.

Last week he was on a bus when an argument erupted between... (independent.co.uk).

He was on a bus – it doesn't matter what bus. The same applies in the example that follows:

"It doesn't. Why would it? I'm nobody." She lowered her chin as her face twisted up. "Just a girl you met on a bus." (Don't Move by Dennis Etchison)

  • 8
    There's nothing wrong with saying "on a bus", though "on the bus" is certainly more common, especially if it is a bus you take regularly.
    – psmears
    Commented Jul 14, 2017 at 11:27
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    I'll add that it's perfectly acceptable to ask a question like "Which bus?" in order to know what bus the person is specifically on.
    – Alexander
    Commented Jul 14, 2017 at 14:08
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    It's funny that in M.Swan's quote, taking a bus is actually used towards the end. Ironic, or what?
    – Tim
    Commented Jul 14, 2017 at 16:32
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    @userr2684291 Your explanation makes sense, I think it really is what most users of English feel when they reflect on and interpret their use of such fixed expressions. I want to add that this general use of a definite article is not restricted to English. In German and in my second language Luxembourgish, we use/imply the same definite article when we refer to these common experiences! The same holds for phrases like "the butcher's", "the doctor", etc. We even use it for "school", where English has not even an article.
    – user54542
    Commented Jul 15, 2017 at 13:19
  • @AshwinSchumann For what it's worth, there are situations that call for using the definite article w/ "school". A kid is "at school" but, after the fight breaks out, his father will explain to the missus that he's "at the school" talking to the teachers; the first is actually describing an activity or state, the latter the location.
    – lly
    Commented Jul 15, 2017 at 14:14

Both are equally acceptable. "On the bus" is usually used in situations where the bus is something the person commonly uses. "On a bus" is used more for one-off type situations.


Why are you so grumpy this morning? Some idiot on the bus kept bothering me.

My parents met on a bus to New York City.

Again, these are not strict rules. Just how they seemed to be used.


Both are correct but express subtle differences.

I'm on the bus. I'll be there in 20 minutes.

Expresses that you are on a specific bus that is meaningful to the conversation. In this case, the assumption is the listener is likely aware of which bus or route you're on so the 20 minute expectation is reasonable.

I'm on a bus. The cell service is really bad.

Expresses that while you are on a bus, it doesn't matter which bus or route, just that your on a bus and that is why you cell service is poor.

  • This is my favorite answer. The article "the" specifying a precise or known context and the article "a" obfuscating the issue. Maybe it's because I grew up in a family full of lawyers! "On the bus" implies the listener knows which bus the speaker is on. "On a bus" implies the listener might not know and the speaker doesn't want to reveal it.
    – JBH
    Commented Jul 15, 2017 at 4:36

If your friend was speaking about how she was travelling at that particular moment in time, then generally in the North of England, 'on the bus' is what one would say. On a bus is not incorrect, because your friend is certainly on a bus, but it is not the usual way to say that one is travelling by bus.

If your friend was not sure that she was on the correct bus for her journey then 'on a bus' would be more appropriate. She is on a bus but it might not be definitely the bus that will get her to where she wants to be.


You could have asked her, "What do you mean you're on the bus? Which one are you on?" And she would have said something like, "Well I'm on the 29 of course, the one I always take to get home."

The definitive article is indeed the one to use here. It's not just any old bus, even though it might actually be a different vehicle, it is one that follows the route she takes every day.

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