Suppress vs. Repress vs. Oppress

Suppress, repress and oppress have similarities and differences .Each is a synonym for the others. Yet the there is a slight difference between  them .Although they are very similar in meaning there are small distinct differences governing their proper use so that they can be interchangeably used in many occasions especially the two former and particularly when they are used in political context.but they each have unique distinctions:

Similarities

1- Suppress and repress mean to stop yourself from showing your feelings:

- He could not suppress/repress a cry of pain as his knee hit the wood.

- It will be impossible for him to suppress/repress the desire for revenge.

- They cannot suppress/repress feelings of amazement at the wonderful world.

- He is in a hurry.' True," said Tom, unable to suppress/repress a smile.

- Those who had said they would suppress/repress their anger showed a death rate 2 times those who express it.

2- They are used to indicate that a government uses force or violence ruthlessly to stop people from opposing:

A- The court found him guilty of trying to suppress/repress demonstrations during last May's uprisings.

B- The uprising was ruthlessly suppressed/ repressed.

C- The army was prepared to suppress / repress rebellion by shooting down the protesters.

D- The government suppressed/repressed the citizens,peasants,...

Oppress has a near meaning with suppress and repress :

To treat people who are less powerful in an unfair and cruel way especially by keeping them from having the same rights that other people in society have :


- The regime is accused of oppressing religious minorities.
- The tyrant oppressed the citizens .
- The government oppresses political activists.


 The former two have a wider range of meaning and can be used in the above contexts instead of oppress but the meaning slightly differs; these words don’t mean exactly the same thing:
Take the sentences A-D, oppress only can be interchangeably used with suppress and repress in sentence D. 

 

3- The two are synonymous in this sense: To inhibit (unpleasant or painful ideas or memories) to avoid considering it:

- He had suppressed/repressed the painful memories of his childhood.

-…the agonizing fear and rage she had had to repress/suppress when she was ten years old and came home.

-.. latent reaction to injuries he had to repress/suppress when a child.

However, they cannot be used interchangeably in this use because:
Suppress means to consciously dismiss from the mind (unacceptable ideas, impulses, etc.):

- I tried to suppress these unpleasant memories.

Repress means to suppress (painful, unpleasant, disturbing memories or thoughts) in oneself automatically or unconsciously from the conscious mind, to stop remembering:

- Children do not normally repress the thought of death.

- The thought that he had killed his brother was so terrible that he repressed it .

For more information about the difference between suppression and repression in this sense click here.

Differences

The two each have their unique senses:

4- Suppress is used to indicate that an authority keeps important information, opinions, or books from being revealed, published, or circulated:

- The police were accused of suppressing evidence.

- The government attempted to suppress any reports of anti-social behavior by the oppositions.

5- Suppress means to prevent a physical process or reaction from happening or developing:

a) to restrain from a usual course or action <suppress a cough,appetite>
b) to inhibit the growth or development of:

- Use of the drug suppressed the immune response.
- The virus suppresses the body's immune system.

Repress means to inhibit the natural development or self-expression of (someone or something):
- Too much bureaucracy represses creativity/a child.