I’ve got an honest question for you all. I’ve searched the archives, searched google and so forth and couldn’t find a straight answer.
So my question is:
What are the differences or similarities between ‘repress’, ‘oppress’ and ‘suppress’? How can each word be used in a sentence to show me their meanings?
Thankee 
They may have overlapping meanings to some extent and this is reflected in dictionary definitions.
“Repress” is something you do yourself.
— “I repressed my instinct to argue with the parking meter officer when he wrote me a ticket.”
“Suppress” is usually something you do to someone or something else, often with force. It often relates to the ability of individuals or groups to express themselves in public.
— “Specially equipped riot police supressed the demonstration at the World Bank meeting.”
— “The authoritarian government supressed freedom of the press.”
— “The cabinet secretary suppressed the results of the study, which might have embarrassed the administration.”
“Oppress” is a more general term relating to a general policy of preventing a person or a group of people or all the people from exercising human rights. It might include a variety of forms of oppression.
Are you familiar with the concept that words don’t necessarily have hard-and-fast differences, but “clouds of meaning”? This is the idea that words have “fuzzy” boundaries, that may overlap all or in part with other words.
The Oxford English Dictionary, in defining one of the senses of “repress” uses “supress” as a synonym. One sense of “oppress” also uses “supress” as a synonym.
But “oppress”, for example, has the additional sense of weighing down by pressure.
Using “oppress” could mean specifically that “repress” was not intended. Or using “oppress” could mean that more than one sense of the word is implied.
“Surpress” can mean to “keep something secret”, whereas “oppress” does not. Same situation as above. Is a word chosen specifically because it doesn’t mean the same as a synonym sense? Or not?
The best way to answer questions like this (because people end up with their own opinions) is to get the “Webster’s Third New International Dictionary” or the “Oxford English Dictionary” unabridged.
Partly_warmer is correct. The comments I gave above are, as I noted, generalisations about usual connotations. Each of these words can carry differing meanings based on context and some of those meanings overlap.
Good advice, but worth looking at from another perspective.
Webster’s Third is an excellent dictionary but has limitations: it is nearly 10 years old, and it is oriented towards British English. The latter may not be such a shortcoming for someone from Australia (like the OP), but for a great many people (including, I suspect, the majority of the readers of this board) a dictionary like the American Heritage Dictionary of the English Language would be a better choice, as it emphasizes American English usage, spelling, pronunciation, etc. A note: this is not an “unabridged” dictionary in the tradition of Webster’s Third, but it certainly would have been up to this task. Currently, the American Heritage is in it’s 4th edition.
Also, it is worth noting before you dial up Borders looking to nab yourself a copy of the OED that the current bound edition is 20 volumes as lists at US$3000, though Amazon has it for US$995. There is a software version “3.0” available for US$295.
Pardon my typo:
[QUOTEthe current bound edition is 20 volumes and lists at US$3000[/QUOTE]
To be really up-to-date for British English, get the OED, and the supplements released over the last few years. The compact OED is available for a couple hundred+, and used copies of the older version for about a hundred. The supplements are expensive, and unnecessary for most purposes.
THE Webster’s is useful in that quite a few people treat it as the American gold standard, so to speak.
I haven’t used my American Heritage for some years, not because it’s poor, but because it’s incomplete when digging deeply. People on the SDMB frequently ask questions that exhaust even the most comprehensive sources.
But it’s worth noting for the sake of the OP that when you get into discussions about the differences of quite similar words such as the ones you’ve asked, you’ll end up baffling 90% of the audience if you’re trying to be tricky. There are plenty of people out there who want words to mean some particular things, and just those. Treating words as having fluid meaning is fine with poets, for example, but doesn’t appeal to some military and scientific dispositions. In my experience, that is.