1. Pertaining to the stars; containing stars; measured by the seeming movements of the stars. Sidereal year, the period in which the earth makes one revolution in its orbit with respect to the stars.

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

• sieral,
• severeal,
• sivreal,
• sideroad,
• sereal,
• sireal,
• svereal,
• diereal,
• federeal,
• litereal,
• siderail,
• indereal,
• sadlereia,
• aidereal,
• zidereal,
• didereal,
• sidreal,
• sydereal,
• sidereel,
• diairal

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

The plural form of "sidereal" is "sidereals".

The singular form of the word "sidereal" is "sidereal". The word does not change when referring to a singular noun.