Related Clues:

• Kind of acid
• ___ oxide (laughing gas)
• Laughing gas, for short
• No sweet tin is overturned in a chemical way
• Dentistry number, familiarly
• Laughing gas, familiarly
• What confuses it with N or us with N?
• -- oxide (laughing gas)
• — oxide (anesthetic)
• Containing nitrogen, especially in a low valency state