monotonous
     adj 1: sounded or spoken in a tone unvarying in pitch; "the owl's
            faint monotonous hooting" [syn: {monotone}, {monotonic}]
     2: tediously repetitious or lacking in variety; "a humdrum
        existence; all work and no play"; "nothing is so
        monotonous as the sea" [syn: {humdrum}]
Source: WordNet® 2.0