Bright (brillant), round (rond), warm (chaud) and rough (rugueux) are four terms vastly used in the French language for sound description in sound creation processes such as music performance, orchestration, sound engineering or sound design, yet they lack formal, standardised definitions. Therefore, the intent of the present study is to obtain definitions and matching sound samples of these four terms as they are interpreted by different sound professionals. This work was organized around individual interviews with 32 sound professionals (musicians, composers, sound designers, acousticians.. .), during which they were asked to give definitions of the four terms and to discuss their opposite concepts. The analysis of the interview verba-tims through qualitative analysis and standard NLP (Natu-ral Language Processing) methods allows us to unravel the various sound description strategies. Based on literature review on timbre semantics we reveal relevant categories for the clustering of the descriptions across the four terms. These categories mainly group acoustic, source-related and metaphorical descriptions produced by the sound professionals. The experts were also asked to choose sound samples from a musical instrument database to complete the definition of each word. By analyzing the descriptions and comparing them to the selected sound samples, we formulate definitions of the four terms along with a few hypotheses on the acoustic correlates involved, thus assessing the potential plurality of perception among the experts.