Explicit, express, specific, definite, categorical are comparable when applied to statements, utterances, and language and when meaning perfectly clear in significance or reference.
Something is explicit which is stated so plainly and distinctly that nothing is left to be inferred or to cause difficulty by being vague, equivocal, or ambiguous.
Something is express which is both explicit and is uttered or expressed with directness, pointedness, or force.
Something is specific which is perfectly precise in its reference to a particular thing or in its statement of the details covered or comprehended.
Something is definite which leaves no doubt as to its reference or to its details or as to what is excluded; definite, far more than specific, suggests precise and determinate limitations.
In practice specific and definite are often used interchangeably without loss; but specific may be preferred when the intent is to stress particularization of reference or specification of details, and definite when it is to emphasize clear limitations; thus, a worker may be given specific instructions about the sequence in which his tasks are to be performed but a definite order not to smoke on the job.
Categorical (see also ULTIMATE 2 ) implies explicitness without the least suggestion of a qualification or condition; thus, a categorical answer is demanded of a person testifying in court when he is compelled to answer yes or no; a categorical denial is a denial that is complete and contains not the slightest reservations.