In Autumn 2020, the Belgian association Wallonie Design dedicated to promoting design published a call tender to define and illustrate more than 100 words used in design practice. This Lexicon aims to complete an existing set of internal mediation tools, developed by the association to better explain the potential and benefits of design to different stakeholders and to promote design by and for other professions. Inter’Act research lab of University of Liege specialized in design and architectural research conducted this two-months project called “the Walloon Design Lexicon”. It was developed through a collaborative writing process, a call for illustrative examples and two workshops. Through these participatory activities, the scale gap between words and practice revealed other intern and inter-professional communicational scale issues. The debate on the words generated a precious knowledge on design practice and designers in a macro (design industry) and global scale (economy of innovation).