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PSAT 8/9 vocabulary: certainty and doubt.

26 words about certainty and doubt — each with a definition, an example sentence, and a memory cue.

26 words · Free PDF · No account needed

The PSAT 8/9 tests vocabulary in context: a Reading and Writing question gives you a passage and asks which word fits, and the wrong answers are usually words that are close in meaning. Studying a whole theme at once is what builds that discrimination — you learn not just what each word means, but how it differs from its neighbors.

Read the definition, then the example, then the memory cue. Come back a few days later and cover the definitions — recalling a word cold is what fixes it, and rereading it is not.

The 26 words

Alphabetical. Everything in the Certainty & Doubt guide.

01
certainadjective

known for sure; established beyond doubt

It is certain that changes will occur, shaping how confidently the people involved could reach a defensible conclusion.

Memory cueA certain fact stands beyond doubt beneath a locked check mark.

02
chooseverb

to select from available options

You may choose any dessert from the menu, making the degree of certainty clear from the surrounding circumstances and available evidence.

Memory cueA hand reaches past several options and picks one; that deliberate selection is to choose.

03
concludeverb

to bring to an end; to reach a decision through reasoning

Based on the data, we can conclude that the treatment is effective, making the degree of certainty clear from the surrounding circumstances and available evidence.

Memory cueConclude by crossing the finish line or by following reasoning arrows to a final decision.

04
confidentadjective

having strong belief in oneself or something (also: feeling certain about something)

She felt confident about her chances of winning the competition, leaving the audience to weigh carefully what could and could not be known.

Memory cueA confident person plants both feet firmly and trusts their ability before beginning.

05
confirmverb

to establish the truth or correctness of something

Please confirm your attendance by Friday, making the degree of certainty clear from the surrounding circumstances and available evidence.

Memory cueConfirm a claim by checking it twice and pressing a solid TRUE stamp.

06
convincedadjective

completely certain about something

She was convinced of his innocence, leaving the audience to weigh carefully what could and could not be known.

Memory cueA convinced mind places an unshakable CERTAIN seal on the conclusion.

07
decidingverb

making a choice or reaching a conclusion about something

After much deliberation, she was finally deciding which university to attend, leaving the audience to weigh carefully what could and could not be known.

Memory cueDeciding means standing at a fork and selecting one path after considering both.

08
decisionnoun

a conclusion or resolution reached after consideration

The committee announced their decision to approve the new policy, shaping how confidently the people involved could reach a defensible conclusion.

Memory cueA decision is the final check mark placed beside one considered choice.

09
determinedverb/adjective

having made a firm decision; resolved; having discovered through investigation

The determined athlete trained for months to compete in the marathon, leaving the audience to weigh carefully what could and could not be known.

Memory cueA determined person locks onto a decision; a detective determines a fact by pinning down evidence.

10
doubtsnoun/verb

feelings of uncertainty; questions or reservations

She had serious doubts about the accuracy of the financial report, leaving the audience to weigh carefully what could and could not be known.

Memory cueDoubts are small question marks that keep certainty from closing the case.

11
ensuringverb

making certain that something happens or is the case

Quality control is essential for ensuring customer satisfaction, leaving the audience to weigh carefully what could and could not be known.

Memory cueEnsuring a result means fastening a safety lock around the final check mark.

12
guessverb

to estimate or suppose something without sufficient information to be certain

I can only guess what he meant by that cryptic message, making the degree of certainty clear from the surrounding circumstances and available evidence.

Memory cueA guess chooses beneath a question mark because there is not enough information for certainty.

13
indicatornoun

a thing that indicates the state or level of something

Rising unemployment is often an indicator of economic trouble, shaping how confidently the people involved could reach a defensible conclusion.

Memory cueAn indicator is the gauge needle that reveals a machine's current state or level.

14
inevitableadjective

certain to happen; unavoidable

Change is inevitable in a rapidly evolving industry, shaping how confidently the people involved could reach a defensible conclusion.

Memory cueAn inevitable train has only one track and must arrive at its destination.

15
opinionnoun

a personal view or judgment not necessarily based on fact

In my opinion, the book was better than the movie adaptation, making the degree of certainty clear from the surrounding circumstances and available evidence.

Memory cueAn opinion belongs inside one person's thought bubble rather than under a universal FACT stamp.

16
positiveadjective

with no possibility of doubt; certain

She was positive she had seen him before, shaping how confidently the people involved could reach a defensible conclusion.

Memory cueA positive answer carries a firm YES with no possibility of doubt.

17
predictedverb

stated that something would happen in the future

Scientists predicted the storm would make landfall by evening, leaving the audience to weigh carefully what could and could not be known.

Memory cueA forecast arrow showed the future event before it happened; it was predicted.

18
predictionnoun

a statement about what will happen in the future

Her prediction about the election results proved to be accurate, leaving the audience to weigh carefully what could and could not be known.

Memory cueA prediction is a statement placed on tomorrow's calendar before the event occurs.

19
probabilitynoun

the likelihood that something will happen

There is a high probability of rain tomorrow according to forecasts, shaping how confidently the people involved could reach a defensible conclusion.

Memory cueProbability is the needle on a likelihood gauge running from impossible to certain.

20
questionnoun/verb

a sentence or phrase used to find out information; to ask or express doubt about something

She raised an important question during the meeting, making the degree of certainty clear from the surrounding circumstances and available evidence.

Memory cueA question mark asks for information and can also cast doubt on a claim.

21
questionedverb

asked questions of someone; expressed doubt about something

The detective questioned the witness for several hours, shaping how confidently the people involved could reach a defensible conclusion.

Memory cueThe witness was asked for answers while the claim's truth was also questioned.

22
realisticadjective

having a sensible and practical idea of what can be achieved; representing things as they actually are

We need to set realistic goals for the project, shaping how confidently the people involved could reach a defensible conclusion.

Memory cueA realistic plan keeps both feet on solid ground and depicts things as they are.

23
selectverb/adjective

to carefully choose as being the best or most suitable

Please select the items you wish to purchase, making the degree of certainty clear from the surrounding circumstances and available evidence.

Memory cueSelect by comparing the alternatives and placing a check beside the best fit.

24
suspectnoun/verb/adjective

to believe something is likely or true without proof; a person thought to be guilty

Police suspect the fire was started deliberately, leaving the audience to weigh carefully what could and could not be known.

Memory cueA suspect stands beneath an evidence question mark because guilt is believed but not proved.

25
uncertainadjective

not able to be relied on; not known or definite

The outcome of the election remained uncertain until the final votes were counted, leaving the audience to weigh carefully what could and could not be known.

Memory cueAn uncertain answer balances between two question marks with no firm footing.

26
uncertaintynoun

the state of being unsure or doubtful; something that is not known

There was great uncertainty about what the future would bring, leaving the audience to weigh carefully what could and could not be known.

Memory cueUncertainty is fog surrounding a decision that cannot yet be known.

Prefer paper? The printable Certainty & Doubt guide has all 26 words, ready to print. All 30 themes (479 words) are on the guide index; for the alphabetical reference, see the PSAT 8/9 vocabulary list.

Knowing the words is step one — seeing them tested is step two.

Test Ninjas puts these words back into real passages — a complete PSAT 8/9 course, practice questions, and an explanation on every answer.