Meaning of "up" in Essential English Dictionary

up

adverb, preposition uk /ʌp/

A2 towards or in a higher place:

He ran up the stairs.
She looked up and smiled at me.

A1 vertical or as straight as possible:

He stood up.
She sat up.

to a greater degree, amount, volume, etc.:

Can you turn up the heat?

used to say that someone completes an action or uses all of something:

I used up all my money.
Eat up the rest of your dinner.
up the road, street, etc.

A2 along or further along the street, road, etc.:

They live just up the road.
go, walk, etc. up to someone/something

B1 to walk directly towards someone or something until you are next to them:

He came straight up to me and introduced himself.
up to 10, 20, etc.

B1 any amount under 10, 20, etc.:

We can invite up to 65 people.
up to/till/until

B1 until a particular time:

You can call me up till midnight.
be up to someone

B1 If an action or decision is up to someone, they are responsible for doing or making it:

I can’t decide for you. It’s up to you.
be up to something informal

B1 to be doing or planning something bad:

What are you two up to?

(Definition of “up adverb, preposition” from the Cambridge Essential Dictionary © Cambridge University Press)