1. In the first place.

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

• forstry,
• firsty,
• firstd,
• firstble,
• flirtly,
• firslt,
• firsted,
• firsta,
• firstlly,
• firtsly,
• firtle,
• firstley,
• firslty,
• fisrtly,
• firtly,
• fristly,
• firsly,
• firstl,
• firstt,
• firstof

• first-year,
• first aid,
• fist,
• firestone,
• first,
• firestine,
• first off,
• first lady,
• first step,
• firstborn,
• firestorm,
• firsthand.

The adjective form of the word "firstly" is "first"

The plural form of "firstly" is "firstlies".

The singular form of the word "firstly" is "first"