Example sentence:

Harry moved his head over on the pillow. In the bed to his right lay Hermione. Moonlight was falling across her bed.

My research:

According to various dictionaries, the definition of "across" varies:

  1. Covering whole area of something.
  2. Covering parts (but not whole) of area.

Is there any rule to figure which definition should be used in what context, for example in this context?

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – tchrist
    Dec 26, 2022 at 16:21
  • The key to solving this is to consider what difference would it make if sense 1 or 2 was involved. It may be that it's important to know that the whole room was bathed in moonlight, making it too bright to sleep - if that's mentioned in the next sentence, we have evidence. But probably the difference would be minimal or nil, and it's no more important than worrying whether the moon was waxing or waning. (Obviously this isn't an answer because I'm not going to search through seven books to find the context.)
    – Stuart F
    Oct 22, 2023 at 18:35

3 Answers 3


Moonlight was falling across her bed.

across the bed is a prepositional phrase.

As in the Cambridge Dictionary cited in the other answer: from one side to the other

Moonlight was shining across her bed. [from one side to the other of her bed]
Moonlight was spilling across her bed. [from one side to the other of her bed]

Moonlight entering a house or structure is often describing as falling. That is because it is in fact a ray of moonlight. Rays can fall on or across an object. Rays are often also described as spilling or shining: Sunlight was spilling onto the winter porch through the glass.

It is instinctually understood that moonlight is actually a ray of moonlight.


One should probably start with dynamic vs stative usages of across.

Stative, locative usages can involve immediate modification/complementisation of a verb:

  • [1a] Snow lay scattered across the path.

  • [1b] Snow lay scattered across the lawn.

a noun:

  • [2] A bridge across the Thames was now a real possibility.

or more remotely describe where a state obtains:

  • [3] A baguette is not just a baguette, it is a way of life across the Channel.

Examples [2] and [3] obviously refer to the '[connected] to/on the other side' rather than the 'covering every part of' sense; we'll concentrate on other usages.

Dynamic, directional usages (we'll consider the case of immediate modification/complementisation of a verb) include the description of an act of bridging, notionally 2-D:

  • [4a] They flew across the Atlantic.
  • [4a'] They fed out the cable across the lawn.

or of a more general 'widespread coverage', 'throughout' covering event:

  • [4b] They applied the fertiliser across the lawn.
  • [4b'] Snow fell across the outlying fields.

Many examples will be contextually clarified. Here, examples [1a] (probably) and [4a] & [4a'] (nigh on obligatorily) refer to the 'being connected / making a connection to the other side' sense:

Cambridge Dictionary:

across: from one side to the other of something with clear limits, such as an area of land, a road, or a river

whereas [1b] and [4b'] default by pragmatics to the 'widespread' sense:

Cambridge Dictionary:

across: in every part of a particular place or country

It is best to disambiguate, perhaps by verbal context. For instance, all the following virtually force the 'throughout' sense:

  • scattered sparsely across
  • at various locations across
  • found widely across
  • taking place all across ...

But I'm afraid OP wants a quick-and-easy rule (for deducing the sense of 'across' in play) that doesn't exist.

And overall, there will be ambiguous phrasings:

  • They soon started travelling in planes across the Channel.
  • They soon started travelling across the country.

There are two usages of across in play here. Cambridge Dictionary starts out with most direct and simplest definition: "from one side to the other." Note that this says nothing about covering something, but about, well, crossing it. It talks about direction and completion, not about square footage. (In geometry terms, we're talking about a vector with this definition).

At first I forgot about the other usage, and was going to write an answer saying "across doesn't imply anything about coverage." But then I came across the helpful sentence lower in Cambridge's entry: "If something is happening across the country, it is happening in all parts of the country." If I "drive across the country," I certainly don't cover all of it, but if I "spread fear across the country," the understanding is that my effects are widespread.

This meaning is causing you confusion. But I think Merriam-Webster helps narrow it down: their definition for this usage is to equate it to "throughout." This usage doesn't equate to "covering," because "covering" carries too specific of a prepositional intent, communicating that X is "on top of" surface Y. I suggest that you replace "covering" in this definition with Webster's suggestion of "throughout," with the sense of "permeating." To adopt Edwin's illustration, a bridge can't stand throughout the river, and moonlight can't fall throughout a bed.

So where is the "rule to figure which definition should be used in what context"? As is often the case with contextualization, it is less a rule and more an exercise in common sense, but there is a key point. The two usages alter the meaning of the verb; the difference between the two is in whether the verb (and maybe somebody can help me out with the terminology here) has a "quasi-transitive" or "quasi-intransitive"* relationship with the object of "across." What the heck do I mean? Consider:

  • The boat rowed across the river. The boat did something "to" the river, in relation to the river.
  • Rejoicing broke out across the country. Rejoicing just happened, "quasi-intransitively," and the country is simply a location.
  • A bird flew across the street. The bird's flight is directionally related to the street.
  • Flags flew across the country. Flags flew—that is, "were flown," an intransitive use of to fly.
  • Fireworks flew across the city. This one... could be ambiguous, and be taken either way. Either "throughout the city, fireworks were flying," or some whizz-bang rockets made it all the way from city limits to city limits.

In the Harry Potter example, even if it were possible to take a "moonlight fell throughout the bed" reading, it would subtly change the meaning of fall. Whatever this kind of "falling" is, it's not something that happens "to" the bed, just something that happens, and the bed just happens to be the place where it does. This of course is not how "moonlight falls."

So the "rule" you're looking for is: Does the context suggest that the verb has a transitive relationship with the object of "across"? If so, it's the "from one side to the other" definition; if not, the "throughout" definition.

  • * Why am I tying myself up in knots with this "quasi-transitive" business? "The boat rowed across the river"—"across the river" is the direct object, isn't it just a matter of transitive vs intransitive? Well, I'm not sure. "He spread fear across the land"—in this sentence, isn't "across the land" also a direct object? But, I maintain, it's a different kind of relationship than "he spread butter on bread." If I will eat green eggs and ham in a tree, or in a house, or on a train, I'm simply eating, and the prepositional phrases are simply locators. But... are they also direct objects? Unsure Oct 28, 2021 at 15:41
  • 1
    And common-sense indicates that the patch of moonlight stretched from one side of the bedcovers to the other. Oct 28, 2021 at 16:39
  • @KateBunting right—but necessarily from top to bottom as well (as the OP was looking for with "covering") that is, a moonbeam is linear rather than planar. It's certainly more capable of "covering" the bedspread than a boat is the Thames, but it's under no obligation to. :-) Oct 28, 2021 at 16:54
  • Why 'necessarily from top to bottom'? I visualise a rectangular patch of light cast across the bed by the moonlight coming through the gap between the curtains. Oct 31, 2021 at 15:07
  • @KateBunting Dang, I left out a word: "not necessarily." The OP's original confusion was between a definition of "across" that conveys "all the way from one side to the other" vs a definition that conveys "all over, entirely throughout," like "across the land." They were asking about "covering the whole area." The point that I think we're both making here is that the moonlight stretches fully from side to side, but does not necessarily "cover the whole area" (though it might). Oct 31, 2021 at 19:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.