What does "assume" mean?

1. (to suppose without proof) to think that something is true, even though you do not have certain proof. 2. (to take on a role or duty) to begin to have a particular job, responsibility, or power. 3. (to take on a quality or appearance) to start to have a particular quality, look, or way of behaving. 4. (to pretend or feign) to pretend to have a feeling or a way of behaving that is not real.

Is it correct to say "I assumed about his arrival."?

No — say "I assumed he had arrived.". The verb 'assume' usually takes a 'that' clause or a direct object, not the preposition 'about'.

assume

US //əˈsum// UK //ɐsˈuːm// as·sume

1 to suppose without proof (v.)
B1 Intermediate

to think that something is true, even though you do not have certain proof.

to accept something as true or as certain to happen, even without proof or formal verification.

Example

I assumed you were coming to the party because I saw your name on the list.

Example

Psychologists often assume that early childhood experiences significantly shape adult personality, though this premise is frequently debated in modern research.
- suppose
- presume
- surmise
- know
- prove
Pitfall

I assumed about his arrival.

I assumed he had arrived.

The verb 'assume' usually takes a 'that' clause or a direct object, not the preposition 'about'.
2 to take on a role or duty (v.)
B2 Upper Intermediate Formal

to begin to have a particular job, responsibility, or power.

to take on or begin to exercise a role, duty, or responsibility. Transitive; requires a direct object.

Example

The vice president will assume the role of director starting next month.

Example

Upon the sudden resignation of the CEO, the chief operating officer was forced to assume full control of the company's daily operations.
- take on
- accept
- shoulder
- relinquish
- resign

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3 to take on a quality or appearance (v.)
C1 Advanced Literary Academic

to start to have a particular quality, look, or way of behaving.

to take on a particular quality, appearance, or characteristic, often one that is not natural or permanent.

Example

The problem assumed a new importance after the latest news report.

Example

As the sun began to set, the desert landscape assumed a deep purple hue that made navigation difficult for the returning scouts.
- acquire
- adopt
- take on
4 to pretend or feign (v.)
C2 Proficiency Formal Literary

to pretend to have a feeling or a way of behaving that is not real.

to adopt a feigned quality or manner, often to deceive others.

Example

He assumed an air of confidence to hide how nervous he actually felt.

Example

The spy assumed a false identity, complete with forged documents and a convincing backstory, to infiltrate the high-security facility.
- feign
- affect
- simulate

Origin

From Latin assūmō (“accept, take”), from ad- (“to, towards, at”) + sūmō (“take up, assume”).

Idioms3 entries