Attach pseudo- to a word to say it only pretends to be the real thing. But watch the tone, pseudo- usually carries a negative, dismissive connotation. pseudoscience looks like science but doesn't follow its methods, and calling something pseudoscience accuses it of being fake and untrustworthy. A pseudo-intellectual is someone who pretends to be deep or clever but isn't, also an insult. A pseudonym, by contrast, is simply a made-up name a writer uses instead of their real one; here pseudo- is neutral, with no dishonesty implied. On spelling: established single words are written solid (pseudonym, pseudoscience), but when you attach pseudo- to a word yourself, hyphenate it, pseudo-intellectual, pseudo-scientific.
Pseudo-: false or imitation
pseudoscience /ˌsudoʊˈsaɪəns/ — The article warned readers not to trust the pseudoscience behind the diet.
pseudonym /ˈsudənɪm/ — She published her early novels under a pseudonym to protect her privacy.
pseudo-intellectual /ˌsudoʊ ɪntəˈlɛktʃuəl/ — His speech was full of pseudo-intellectual jargon that meant very little.
Not ""She writes under a pseudonym, so she must be hiding something dishonest." (reads the neutral word as an accusation)" — say ""She writes under a pseudonym — simply a pen name, with nothing dishonest implied."". pseudo- is not always an insult: pseudoscience and pseudo-intellectual are negative and dismissive, but pseudonym is neutral. Let the specific word, not the prefix alone, tell you the tone.
Try it: Which word describes a made-up name an author uses instead of their real one? (pseudonym / pseudoscience / counterargument) Answer: pseudonym — 'Pseudonym' is the word for an assumed name, a pen name, which is exactly what an author uses to hide their identity, and it's a neutral word, not an accusation. 'Pseudoscience' means false science, not a name, and 'counterargument' is a reply against a point, unrelated to naming.
Counter-: against or in response
Add counter- to show that something works against, or responds to, something else. A counterargument is a point made against an earlier one; to counteract something is to reduce or cancel out its effect; something counterproductive achieves the opposite of what you wanted. Keep them apart by role: counterargument is the opposing point, counteract is the action of offsetting an effect, and counterproductive describes a result that backfires. All three are neutral in tone and work in both formal and everyday English. The prefix usually attaches with no hyphen.
counterargument /ˈkaʊntərˌɑrɡjəmənt/ — She anticipated the counterargument and addressed it in her opening paragraph.
counteract /ˌkaʊntərˈækt/ — The new policy is meant to counteract rising fuel prices.
counterproductive /ˌkaʊntərprəˈdʌktɪv/ — Punishing every small mistake can be counterproductive and lower morale.
Not ""Her reply was an against-argument to his point." (not a standard English word)" — say ""Her reply was a counterargument to his point." (the fixed form for a response against a point)". Use counter- for something that works against or responds to something else; 'against-argument' isn't a real word. The prefix attaches directly.
Try it: The manager realized that stricter rules were only making the team slower and less willing to try. The rules were ___. (counterproductive / pseudo-intellectual / counterargument) Answer: counterproductive — 'Counterproductive' means it works against the goal, which fits rules that make the team slower rather than faster. 'Pseudo-intellectual' describes fake cleverness, not a bad outcome, and 'counterargument' is a reply against a point, not a description of the rules' effect.
Try it: Which word means to reduce or cancel out the effect of something? (counteract / pseudoscience / pseudonym) Answer: counteract — 'Counteract' pairs counter- (against) with act, so it means to act against and reduce an effect, like offsetting rising prices. 'Pseudoscience' means false science and 'pseudonym' is a false name; neither has to do with cancelling an effect.