WordWeb Online

1. Inspiring scornful pity
   - pathetic, silly
    
2. Incongruous; inviting ridicule
   "her conceited assumption of universal interest in her rather dull children was ridiculous"
   - absurd, cockeyed, derisory, idiotic, laughable, ludicrous, nonsensical, preposterous
    
3. Broadly or extravagantly humorous; resembling farce
   - farcical, ludicrous

See also: foolish, humorous, humourous [Brit, Cdn, non-standard], ridicule, ridiculousness, undignified

Encyclopedia: Ridiculous