Ahmed, Safa'a A2021-01-042021-01-042019-0711102721https://doi.org/10.21608/opde.2018.106586http://repository.msa.edu.eg/xmlui/handle/123456789/4287This paper attempts a new categorisation of omission in simultaneous interpreting through exploring and investigating omission in the simultaneous interpreting of U.S. presidential debates from English into Arabic in order to improve the interpreter's performance. This is not an attempt, however, to answer the question why the interpreter uses omission, intentionally or impromptu, because it is not a cognitive study of the reasons why this phenomenon occurs. Instead, it aims to evaluate omission in real, professional contexts to determine how far omissions convey the functions of presidential debates. The data is collected from the second 2016 U.S. presidential debate between the two candidates Hillary Clinton and Donald Trump. An interdisciplinary approach combining between interpreting studies (especially Pym's Risk Analysis 2008) and political sciences (basically Benoit's Functional Theory of Political Campaign Discourse 2017) is employed. The paper reaches the conclusion that there is a gap in understanding omission in interpreting a discourse type as such from English into Arabic and that interpreters used omission in their renditions, a matter which affected the three functions of presidential debates. Omission should be accounted for in the light of an interdisciplinary approach combining between a multi-layered linguistic and pragmatic analysis, interpreting studies and a functional theory of political campaign discourse. The product and its potential impact(s) for the aims of communication determine the level of functionality entailed in the interpretation: 'functional', 'nonfunctional, or 'semi-functional''. If the interpreter becomes aware of the functions of this discourse type and how it behaves, then his performance should presumably be improved; and at this particular point, further empirical, experimental research is recommended.simultaneous interpretingomissionpresidential debatesfunctional theory of political campaign discoursehttps://doi.org/10.21608/opde.2018.106586