The elaboration of a "specialized" lexicon in a given domain, here the water domain, is developed in the inter-comprehension problematic between the audiences addressed by the users of these lexicons and the audience addressed by the daily media (press and television) in the domain. The domain’s "discursive strata" are the result of words choice and arrangements according to the audience. They account for this problem. The audience addressed in an administrative discourse is not the same audience addressed in a scientific discourse, which allows to make a distinction between the two discursive strata. Other discourses of the domain are inspired by the practice of an art or based on moral (ethics), religious or ideological considerations. They tend to produce a personal commitment, possibly collective. They belong to another discursive stratum called "decisional incitative". The fourth discursive stratum is the current language, used in daily life and by the media. These discursive strata have a specific vocabulary and different approaches of the shared lexicon, which leads to incomprehension and misinterpretation of the words’ meaning. The stratified lexicon is backed by an ontology of the domain knowledge objects. Its concepts are transposed as "pivot" lexical units. These units can be associated with "satellite" lexical units in other discursive strata, with same or nearby labels and different meanings. The non-stratified discursive units give an access to the lexical units defined and exemplified through the lexicon texts. The proper nouns edited in the domain ontology can be lexicalised and exemplified. The conceptual approach of the lexicon is completed by a corpus linguistics approach through the textometry of texts regrouped in corpora, out of documents referenced in the ontology. The textometry fosters recurrent substantives and nominal phrases which can be added when updating the lexicon on new themes and disciplines, along with editing new concepts in the domain ontology. The thesis presents examples of the double process of the lexicon construction : starting from the domain ontology, as a pivot of the lexicon, and from the textometric analysis of textual corpora.The thesis is associated with the Dictionnaire de l’Académie de l’Eau project, or Lexeau® project of a bilingual lexicon in French and in English of water related texts and data. It presents the basis of the project and various aspects of its feasibility.