1. In an imperfect manner or degree.

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

• inperfectly,
• umperfectly,
• jmperfectly,
• kmperfectly,
• omperfectly,
• 9mperfectly,
• 8mperfectly,
• ikperfectly,
• ijperfectly,
• imoerfectly,
• imlerfectly,
• im-erfectly,
• im0erfectly,
• impwrfectly,
• impoerfectly,
• impefectly,
• imprefectly,
• impurfectly,
• imparfectly,
• Unperfictly

• improperly,
• imperiously,
• imperfection,
• impertinently,
• improperness,
• imperially,
• perfectly,
• improper,
• imperfect,
• imperfectness,
• imperforate,
• imperfective,
• imperial.

The adjective form of "imperfectly" is "imperfect".

The plural form of the word "imperfectly" is also "imperfectly" as it is already an adverb and does not change in the plural form.

The singular form of the word "imperfectly" is "imperfectly". The word itself is an adverb, and adverbs do not have singular or plural forms. They remain the same regardless of the noun they modify.