Synonyms of monotonous

Adjective

1. humdrum, monotonous, dull (vs. lively)

usage: tediously repetitious or lacking in variety; "a humdrum existence; all work and no play"; "nothing is so monotonous as the sea"

2. flat, monotone, monotonic, monotonous, unmodulated (vs. modulated)

usage: sounded or spoken in a tone unvarying in pitch; "the owl's faint monotonous hooting"

Definition and meaning of monotonous (Dictionary)