We propose, in this paper, a model for an Ontological and Terminological Resource (OTR) dedicated to the task of n-ary relations annotation in Web data tables. This task relies on the identi cation of the symbolic concepts and the quantities, de ned in the OTR, which are represented in the tables' columns. We propose to guide the annotation by an OTR because it allows a separation between the terminological and conceptual components and allows dealing with abbreviations and synonyms which could denote the same concept in a multilingual context. The OTR is composed of a generic part to represent the structure of the ontology dedicated to the task of n-ary relations annotation in data tables for any application and of a speci c part to represent a particular domain of interest. We present the model of our OTR and its use in an existing method for semantic annotation and querying of Web tables.