1. musically pleasing

Similar word(s): compatible, consonant, harmonic, harmonical, harmonised, harmonized, sympathetic, true, symphonic, symphonious

2. having components pleasingly or appropriately combined.

Similar word(s): balanced, proportionate, symmetrical

3. suitable and fitting

- the tailored clothes were harmonious with her military bearing

Similar word(s): congruent, congruous

4. existing together in harmony

- harmonious family relationships

Similar word(s): compatible