There are many synonyms for the word "bad." Here are some options:

• Atrocious
• Awful
• Defective
• Detestable
• Dreadful
• Faulty
• Gross
• Horrible
• Imperfect
• Inferior
• Junky
• Lousy
• Malicious
• Naughty
• Offensive
• Poor
• Rotten
• Sad
• Terrible
• Unacceptable
• Unfortunate
• Unpleasant
• Unsatisfactory
• Vile

These synonyms were found on various websites, including Thesaurus.com, English Language & Usage Stack Exchange, Merriam-Webster Thesaurus, Collins English Thesaurus, and Dictionary.com.