This PhD thesis is in the framework of Cognitive Science and Pragmatics. The author is interested in metaphorical expressions in verbal communication realized by the everyday use of proverbs and metonymies. The broader perspective is to find out the ability of native speakers of Greek to understand, interpret and use proverbs and metonymies in metaphorical expressions of their everyday communication. The author starts her analysis with the theoretical framework suggested by Laval (1992) and colleagues (1997), which investigated the conceptualization of metaphoric expressions of a tribe in Nigeria. This helps her to approach the perlocutionary acts and treats figurative language as a means of verbal communication and investigates it on the grounds of proverbs and metonymies. She is also interested in the transparency of greek proverbs and metonymies (in other words, if they can be interpreted by the words that constitute them, transparency as evaluated by greek academic evaluators). The core tenet of investigation concerns the extent to which native speakers of Modern Greek conceptualize, interpret and produce metaphors in their everyday speech. Three experimental studies were conducted. In Study I the author has conducted a descriptive analysis and she has attempted to apply the theoretical framework to Modern Greek. She has also tested the degree to which perlocutionary acts can be executed by widespread Greek proverbs and metonymies. In Study II the author has distributed questionnaires to different groups of native speakers of Greek, from different geographical areas and from different social backgrounds. Her goal was to examine the comprehension-interpretation and the comprehension-choice of linguistic metaphors, metonymies and proverbs. In Study III the author analyzed 23 widespread Greek proverbs and metonymies. Moreover, in this Study the author has recorded metaphor ‘transparency’ appreciated by Greek academic evaluators; she has compared their responses to the responses native speakers of Modern Greek have given on the interpretation/comprehension/choice of metaphors (tests conducted in Study II). The results have shown that Laval's (1992) cognitive schema can explain the way Greek speakers accessed the content of perlocutionary acts, executed by 23 widespread proverbs and metonymies. Moreover, the results have shown that certain proverbs and metonymies can be interpreted more easily than others. Subjects who have a “theoretical” profession (such as philologists, lawyers) responded better in the tasks of comprehension-interpretation of proverbs and in the tasks of comprehension-choice of metonymies, than those who have a more “practical” profession (such as electronics, dentists). Another important observation concerns the appreciated ‘transparency’ of the 23 widespread Greek proverbs and metonymies. Last but not least, through her data analysis, the author has constructed a database of proverbs and metonymies, which constituted the core contribution of this PhD thesis. The conceptualization and interpretation of proverbs and metonymies indicates the way according to which we use metaphors and we express our linguistic and general experiences. Moreover, the conceptualization and interpretation of proverbs and metonymies opens a “window” for the understanding of figurative language and helps us to understand our non-literal way of thinking.