Definition of sidereal in US English:

sidereal

adjective

  • Of or with respect to the distant stars (i.e. the constellations or fixed stars, not the sun or planets).

    • ‘It needs remembering that these early cities were all founded in overwhelmingly agricultural societies where the hoe and horse, the field and the farmhouse, and the rhythms of life followed sidereal rather than clock time.’
    • ‘In the first sphere across the zodiac we see twelve sidereal animals.’
    • ‘Slightly brighter today is Alpherg, which is taken as the starting point for the sidereal zodiac.’
    • ‘Obviously, there's a lot more to Vedic astrology than just knowing that there is a sidereal zodiac and a tropical zodiac; when you start learning, you realise all the rules and regulations.’
    • ‘Fixed stars continued to be used as reference points throughout the Middle Ages, and even Copernicus measured positions in a sidereal zodiac beginning from the fixed star Mesartim.’

Origin

Mid 17th century: from Latin sidereus (from sidus, sider- ‘star’) + -al.

Pronunciation

sidereal

/ˌsaɪˈdɪriəl//ˌsīˈdirēəl/