WordWeb Online

1. So lacking in interest as to cause mental weariness
   "tedious days on the train"
   - boring, deadening, dull, ho-hum, irksome, slow, tiresome, wearisome, deadly, unamusing, draggy
    
2. Using or containing too many words
   "tedious speakers"
   - long-winded, verbose, windy, wordy

See also: prolix, tedium, uninteresting