monotone

 
Pronunciation: /ˈmɒnətəʊn/

noun

[usually in singular]
  • a continuing sound, especially of a person’s voice, that is unchanging in pitch and without intonation: he sat and answered the questions in a monotone

adjective

  • (of a voice or other sound) unchanging in pitch; without intonation or expressiveness: his monotone reading of the two-hour report
  • without colour or variety; dull: the monotone housing estates of the big cities

Origin:

mid 17th century: from modern Latin monotonus, from late Greek monotonos