These words refer to a communication that is without ambiguity, vagueness or evasion. With specific , the emphasis is on a lack of vagueness achieved by detailed rather than general treatment; specific instructions on how to cope with every conceivable problem that might come up during his absence. Definite refers to clarity and distinctness or to expression that is conclusive or unconditional: a map that would give him a definite idea of his whereabouts; promising to have a definite yes-or-no answer within a week. As in the last example, definite may indicate extreme brevity, whereas specific tends to suggest exhaustive treatment. Something that is specific , further more, may still be unclear or inconclusive, regardless of its concreteness and detail: a study that was specific in listing possible alternatives but was not definite about which of these might give the best results.

Explicit stresses an exact spelling-out that leaves nothing confusing to be guessed at. When instructions or description are involved, one would normally have to be both specific and definite to be explicit ; on the other hand, if a judgement is involved, one would have to be definite , but not necessarily specific : an explicit list of all campaign expenditures; a brief remark that made explicit his dislike of Picasso. Explicit may tend to relate to questions, definite to answers: an explicit request that he give a definite reply. Express is similar to, but an intensification of, explicit . It suggests emphatic directness that avoids the tacit or evasive: unwilling to disobey an express command. This word, also, is often related to the posing of questions or the stating of one’s desire: his express wish that he be cremated.