1. Having no stars visible or no starlight.

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

• staneless,
• stanless,
• tirless,
• saless,
• stapless,
• strress,
• seatless,
• seadless,
• stailless,
• starles,
• staniless,
• scaless,
• tailess,
• stailess,
• stanleys,
• stayles,
• stailness,
• stalles,
• scorless,
• stepless

• starlet,
• steriliser,
• straley,
• stroller,
• Strahle,
• starlit,
• stroll,
• strahl,
• sterilised,
• storyline,
• sterol,
• sterileness,
• Starla,
• starlike,
• sterilise,
• storlie,
• sterile,
• strelow,
• sterilize,
• starling,
• Strohl.

The adjective form of "starless" is "unstarred".

The plural form of "starless" is "starless". The word does not change when pluralized.

The singular form of the word "starless" is "starless". Since "starless" is already in the singular form and doesn't have a plural counterpart, it remains the same regardless of the subject.