The term 'having no musical key' can be summarized by the word 'ATONAL', which is a six-letter word. Atonality is a type of music that does not conform to any particular key or tonal center. It is characterized by the absence of a tonal center, or key, and the use of dissonance and chromaticism. ATONAL music is often used to create a sense of tension and ambiguity. It is often associated with modern classical music, but it has been used in other genres as well.