1. Having no sleep; wakeful; having no rest; perpetually agitated.

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

• sleepness,
• sleavless,
• speehless,
• sleepyness,
• sleevless,
• sleeples,
• sleveless,
• slefless,
• sleeplesnes,
• stepless,
• aleepless,
• zleepless,
• sleeplees,
• sleeplesss,
• sleepleess,
• sleeplesse,
• slepless,
• cleepless,
• excepless,
• plaecless

• sleeveless,
• slaveless,
• sleepwalk,
• sleepwalker,
• sleeplessly,
• sleep late.

The adjective form of the word "sleepless" is "sleepless".

The plural form of the word "sleepless" is "sleepless." The word does not change in form when used in plural.

The singular form of the word "sleepless" is "sleeplessness"