It just occurred to me that even though "ahead/behind" mean opposite things, their usage is slightly different. Say we were talking about time zones. Why is it that I could say either

I'm two hours ahead of you.


You're two hours behind me.

But both of these are wrong:

I'm two hours ahead you.

You're two hours behind of me.

Since these words are perfect opposites, it seems like they should follow the same pattern. So that either "ahead of you" and "behind of you" would both be correct, or "ahead you" and "behind you" would both be correct.

There are even other cases where these two words do match each other in the prepositions they use. For example, if I'm no longer talking about time zones, and I'm instead talking about my progress at work, I could say either

I'm ahead on my work.


I'm behind on my work.

  • What do you think the be- in behind is for?
    – Kris
    Dec 5, 2018 at 6:18

3 Answers 3


They weren't always "perfect opposites". In Middle English (and earlier, I believe), the "perfect opposite" of "behind" was "before". In fact, there were several collocations as a result (from the MED): "bihinde and bifore, in back and in front; on all sides, in all directions; bihinde ne bifore, nowhere". Actually, they are still opposites, even today. Here's a quote showing both as opposites:

Julius him wes bi-foren, Androgeus bi hinden.
"Julius was before him, Androgeus behind."
Laʒamon's Brut, c1275(?a1200)

At some point in Middle English, another adverb was created, "on head". It meant "impetuously, rashly, unadvisedly". Flash forward to the beginning of Early Modern English and we finally see "on head" (and its new spelling, "ahead") being used to mean "in front of". But significantly, it was used both with and without "of":

The one place must be thwarte of you, the other must be a head or sterne of you.
A regiment for the sea, ?1574

These ships wyll goe well a head the sea, that is to say, the Ship to stande close by the winde in such places as the grating of the tyde doth cause the sea to come agaynst the head or bowes of the Ship.
Treasure for Traueilers, 1578

According to the OED, "ahead" as a preposition is "rare after 17th cent."

  • Just look up a good dictionary for the simple answer to this Q. Good Luck.
    – Kris
    Dec 5, 2018 at 10:11

This is an interesting question.

One clue may be the prefix ‘be’ in ‘behind’. Because there are other words with this prefix:-

before; below; between; beyond; below.

None of these need ‘of’.

But this is not only true of the prefix ‘be’. Some words with the initial ‘a’ work the same way.

*about; around; amidst; *

None of these need ‘of’, either.

So let’s look at etymology. Etymonline gives the ‘a-‘ prefix the following “a-(1) explanation relevant to the question.

a- (1) prefix or inseparable particle, a relic of various Germanic and Latin elements. In words derived from Old English, it commonly represents Old English an "on, in, into" (see on (prep.)), as in , above, , ahead, , , etc., forming adjectives and adverbs from nouns, with the notion "in, at; engaged in." In this use it is identical to a (2).

Those in angled brackets I take to be irrelevant to our question. But ‘above’ is similar, and that is not normally (or ever?) followed by ‘of’. There is ‘astern of’ where what seems to be involved is a naval expression meaning ‘at the stern of’. It is possible that in the same way, ‘ahead of’ is short for ‘at the head of’. But then we should have to explain why ‘amid’ has no ‘of’.

So we are left with the possibility that it is just an accident of usage: a good instance of how the speech habits determine the rules and not vice versa!


My dictionary says:
ahead ADVERB

So there is no reason that they should be similar in their usage.

  • Not in the second case, though. Which is your dictionary, btw?
    – Kris
    Dec 5, 2018 at 10:08

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