This research paper is devoted to explication of understanding of proof in English and American law by means of study of its evolution and current condition. To get this aim the comparative analysis of few similar fragments from the Black’s law dictionary is completed.
 It is concluded, firstly, that concept of judicial proof grasps both process of presentation of legal evidence and its effects – conclusion, supported by system of the evidence, and belief to this conclusion, induced in minds of relevant persons.
 Secondly, cluster of (concepts and relevant) terms, by which proof in English and American law is (realized and) expressed, includes, among others, «truth», «proof» and «evidence», «to prove» and «to evidence», «burden of proof», «degree of proof», «standard of proof», «standard of proof beyond reasonable doubt», «standard of proof by preponderance of the evidence», «standard of proof by clear and convincing evidence», «legality», «admissibility», as well as «belief», «conviction», «to convince» and «to persuade».
 Thirdly, this cluster had been shaped and develops further – in addition to natural space and time – in at least three dimensions: logical, legal, and rhetorical. If during the late XIX – the first half of the XX century in this cluster were prevailing that was laying in logical and legal dimensions, then since the middle of XX century there is an expansion of rhetorical content through, at least partially, extrusion of the logical.
 Fourthly, on this way the concept of judicial proof has lost – as necessary components of its content – immanent signs of the logical proof, namely, truth of the premises-evidence and necessary logical connection between system of the evidence and conclusion. Concept of standard of proof has undergone significant change: it is divided into three subordinate concepts, usage of which depends on situation. And even those of these subordinate concepts, which correspond to criminal cases and include the strongest requirements, do not require truth or absolute certainty of the conclusion, agreeing only on absence of reasonable doubt that by nature is subjective and practically never avoid some dependence on rhetorical influence.
 Finally, the history of understanding and expression of legal proof shows that real legal proof goes more and more away from its analog in logic.