Origin: 1520–30; < Gk
harmónios melodious, lit., fitting.
See harmony, -ous 
Related forms: har⋅mo⋅ni⋅ous⋅ly, adverb
har⋅mo⋅ni⋅ous⋅ness, noun
Synonyms:
1. amicable, congenial; sympathetic. 2. concordant, congruent, consonant, consistent.
Antonyms:
1, 3. discordant.