Disembodied electronic sounds constitute a large part of the modern auditory lexicon, but research into timbre perception has focused mostly on the tones of conventional acoustic musical instruments. It is unclear whether insights from these studies generalize to electronic sounds, nor is it obvious how these relate to the creation of such sounds. This work presents an experiment on the semantic associations of sounds produced by FM synthesis with the aim of identifying whether existing models of timbre semantics are appropriate for such sounds. A novel experimental paradigm, in which experienced sound designers responded to semantic prompts by programming a synthesizer, was applied, and semantic ratings on the sounds they created were provided. Exploratory factor analysis revealed a five-dimensional semantic space. The first two factors mapped well to the concepts of luminance, texture, and mass. The remaining three factors did not have clear parallels, but correlation analysis with acoustic descriptors suggested an acoustical relationship to luminance and texture. The results suggest that further inquiry into the timbres of disembodied electronic sounds, their synthesis, and their semantic associations would be worthwhile and that this could benefit research into auditory perception and cognition and synthesis control and audio engineering.