across

which word?
Across or over? We can use across or over to mean 'on or to the other side': I ran across the road. • I ran over the road. We usually use over to talk about crossing something high: Adam climbed over the wall. With 'room' we usually use across: I walked across the room.

Longman Dictionary of Contemporary English

across

a‧cross S1 W1 /əˈkrɒs $ əˈkrɒːs/ BrE AmE adverb, preposition
[Date: 1200-1300; Language: Anglo-French; Origin: an crois 'in cross']
1. from one side of something to the other:
the first flight across the Atlantic
They ran straight across the road (=without stopping).
We’ll have to swim across.
We’d got halfway across before Philip realized he’d left his money at home.
We gazed across the valley.
2. towards someone or something on the other side of an area:
There’s Brendan. Why don’t you go across and say hello?
across to/at
The referee looked across at his linesman before awarding the penalty.
He walked across to where I was sitting.
3. used to say that something exists or reaches from one side of an area to the other:
a deep crack across the ceiling
the only bridge across the river
Do you think this shirt is too tight across the shoulders?
Someone’s parked right across the entrance to the driveway.
4. on the opposite side of something:
My best friend lives across the road.
He knew that just across the border lay freedom.
across (something) from somebody/something
Across the street from where we’re standing, you can see the old churchyard.
the woman sitting across from me (=opposite me) on the train
5. in every part of a country, organization etc:
a TV series that became popular across five continents
Teachers are expected to teach a range of subjects right across the curriculum.
6. used to show how wide something is
ten feet/five metres etc across
The river is 2 kilometres across.

Oxford Advanced Learner's Dictionary

preposition
1. from one side to the other side of sth
• He walked across the field.
• I drew a line across the page.
• A grin spread across her face.

• Where's the nearest bridge across the river?

2. on the other side of sth

• There's a bank right across the street.

3. on or over a part of the body
• He hit him across the face.

• It's too tight across the back.

4. in every part of a place, group of people, etc.
Syn: throughout
• Her family is scattered across the country.
• This view is common across all sections of the community.
Word Origin:

[across] Middle English (as an adverb meaning ‘in the form of a cross’): from Old French a croix, en croix ‘in or on a cross’, later regarded as being from a- ‘to, towards’ + cross.

Cambridge Advanced Learner's Dictionary

Cambridge Advanced Learner's Dictionary - 4th Edition

across / əˈkrɒs / / -ˈkrɑːs / preposition

A2 on the opposite side of:

The library is just across the road.

in every part of a particular place or country:

Voting took place peacefully across most of the country.

Collins Advanced Learner’s English Dictionary

across

/əkrɒs, AM əkrɔ:s/

Frequency: The word is one of the 700 most common words in English.

Note: In addition to the uses shown below, 'across' is used in phrasal verbs such as ‘come across’, ‘get across’, and ‘put across’.

1.
If someone or something goes across a place or a boundary, they go from one side of it to the other.
She walked across the floor and lay down on the bed...
He watched Karl run across the street to Tommy.
...an expedition across Africa.
PREP
•
Across is also an adverb.
Richard stood up and walked across to the window.
ADV: ADV after v

2.
If something is situated or stretched across something else, it is situated or stretched from one side of it to the other.
...the floating bridge across Lake Washington in Seattle...
He scrawled his name across the bill...
PREP
•
Across is also an adverb.
Trim toenails straight across using nail clippers.
ADV: ADV after v

3.
If something is lying across an object or place, it is resting on it and partly covering it.
She found her clothes lying across the chair...
The wind pushed his hair across his face.
= over
PREP

4.
Something that is across something such as a street, river, or area is on the other side of it.
Anyone from the houses across the road could see him...
When I saw you across the room I knew I’d met you before.
PREP
•
Across is also an adverb.
They parked across from the Castro Theatre...
ADV: ADV after v, usu ADV from n

5.
If you look across at a place, person, or thing, you look towards them.
He glanced across at his sleeping wife...
...breathtaking views across to the hills.
ADV: ADV after v, oft ADV prep

6.
You use across to say that a particular expression is shown on someone’s face.
An enormous grin spread across his face...
= over
PREP

7.
If someone hits you across the face or head, they hit you on that part.
Graham hit him across the face with the gun.
PREP

8.
When something happens across a place or organization, it happens equally everywhere within it.
The film ‘Hook’ opens across America on December 11...
PREP

9.
When something happens across a political, religious, or social barrier, it involves people in different groups.
...parties competing across the political spectrum...
across the board: see board
PREP

10.
Across is used in measurements to show the width of something.
This hand-decorated plate measures 30cm across...
ADV: amount ADV

Merriam-Webster's Advanced Learner's Dictionary

¹across /əˈkrɑːs/ prep
1 a : from one side to the other side of (something)
• We took a ferry across the river.
• We saw them walking across the street.
• She reached across the table to shake his hand.
• They traveled back and forth across the border.
• Airplanes flew across the sky above us.
• She slapped him right across the face. [=she slapped his face]
b : on the other side of (something)
• He was seated across the table from me.
• Our grandparents live across the street (from us).
• The accident happened just across the state line.
2 : so as to reach or spread over or throughout (something)
• A smile spread across her face.
• Looking out across the ocean, he saw land.
• The sun's light spread across the mountains.
• The disease spread quickly across the country.
3 : in every part of (a country, region, etc.)
• The movie is now showing in theaters across [=throughout] America.
• Newspapers (all) across the world reported the story.
• We could hear the bells all across town.