1. Irresistible; that cannot be opposed.

2. That can not be resisted.

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

• resistens,
• resstles,
• eesistless,
• desistless,
• fesistless,
• tesistless,
• 5esistless,
• 4esistless,
• rwsistless,
• resistlesss,
• resistlesse,
• reistless,
• resitless,
• resistles,
• resisltess,
• asistless,
• deseretless,
• irressistless,
• iresistless,
• irresisless

• resistivity,
• resistor,
• resistant,
• resistible,
• requisite,
• resister,
• resistance,
• resistive,
• register,
• Reichstein,
• requisiteness,
• registered.

The adjective form of "resistless" is "irresistible".

The plural form of "resistless" is "resistlesses." However, it is worth noting that "resistlesses" is not commonly used, and you may want to consider using different wording to avoid confusion.

The singular form of the word "resistless" is "resistless".