1. In a poisonous manner.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• ooisonously,
• loisonously,
• -oisonously,
• 0oisonously,
• piisonously,
• pkisonously,
• plisonously,
• ppisonously,
• p0isonously,
• p9isonously,
• pousonously,
• pojsonously,
• poksonously,
• poisinously,
• poisionously,
• poisonusly,
• posionously,
• poisonouslyy,
• poisenously,
• poysinously

• poison gas,
• poisonous,
• poison camas.

The adjective form of "poisonously" is "poisonous".

The plural form of the word "poisonously" is "poisonously." The word itself doesn't change in plural form.

The singular form of the word "poisonously" is "poisonous"