clear and leaving no doubt about the position expressed

Common use: an unequivocal answer / assurance; unequivocal support

The landlord gave an unequivocal assurance that no pets would be removed from the building.

expressed firmly and without qualification

Common use: a categorical denial / refusal / statement

Her categorical refusal ended any discussion of selling the family photographs.

settling the matter sufficiently to support a definite conclusion

Common use: conclusive evidence / proof / result

The recovered serial number provided conclusive proof of which instrument had been stolen.

so strong or clear that it cannot reasonably be disproved; a strong claim

Common use: irrefutable evidence / facts / logic

The recording supplied irrefutable evidence that the bell had sounded before the finish.

established so firmly that uncertainty is excluded in the speaker’s assessment

Common use: establish / show something beyond doubt

The extra rehearsal demonstrated beyond doubt that the understudy knew the role.

a firmly held belief or confidence; not itself evidence that the belief is true

Common use: a deep / personal conviction; speak with conviction

He spoke with conviction about the value of preserving local dialects.

not firmly decided or stated and open to revision

Common use: a tentative conclusion / suggestion / interpretation

We made a tentative plan to walk the ridge, depending on the weather.

accepted for the present but subject to later confirmation or replacement

Common use: provisional approval / figures / arrangements

The chess club issued provisional rankings while two disputed results were checked.

not allowing a definite answer to the question being investigated

Common use: inconclusive findings / evidence / results

The taste test was inconclusive because the judges split evenly between the two recipes.

not precisely established, fixed or classifiable

Common use: an indeterminate age / period / outcome

A figure of indeterminate age stood behind the frosted glass.

unclear or open to more than one interpretation; sometimes deliberately non-committal

Common use: an equivocal response / answer / signal

Asked whether the theatre would reopen, the owner gave an equivocal answer.

a question open to debate, or, especially in American usage, one with no practical relevance

Common use: whether something is possible is a moot point

With the launch cancelled, which room would have held the guests became a moot point.

check or establish that information is true or accurate

Common use: verify a calculation / detail / identity; verify that

Before printing the programme, Mira verified the spelling of every performer’s name.

establish that something is genuine or that an identity is what it claims to be

Common use: authenticate a manuscript / signature / identity

A specialist authenticated the manuscript by examining its ink and handwriting.

show that something is valid or suitable for its intended use; also officially confirm

Common use: validate a method / model / result / ticket

The team validated the measuring device against a known reference instrument.

check information against another source or method

Common use: cross-check details against records; cross-check one source with another

I cross-checked the trail distances against two independently drawn maps.

provide testimony or evidence for something; relatively formal

Common use: attest to someone’s skill / character; attest to the quality of something

The carefully joined drawers attest to the cabinetmaker’s skill.

determine or demonstrate something sufficiently clearly to treat it as known

Common use: establish a fact / cause / connection; establish whether

It took several visits to establish whether the foxes were using the same den.

indirectly supporting a conclusion through surrounding facts

Common use: circumstantial evidence; a circumstantial case

The muddy footprints were circumstantial evidence of a visitor, but did not identify one.

based on personal accounts or isolated observations rather than systematic investigation

Common use: anecdotal evidence / accounts / reports

Anecdotal reports suggest that the new bus route feels safer after dark.

based on observation or experience rather than theory alone

Common use: empirical evidence / research / findings

The book’s claims about bird migration rest on empirical observations from several continents.

information received from others rather than known through direct experience

Common use: rely on hearsay; dismiss a story as hearsay

I had heard that the gallery was closing, but it was hearsay rather than an official announcement.

a conclusion reached by reasoning from available information

Common use: draw / make an inference; an inference from evidence

From the untouched food, she drew the inference that the visitors had left early.

an idea proposed without adequate evidence to establish it

Common use: pure / informed conjecture; a matter of conjecture

Why the composer abandoned the piece remains a matter of conjecture.