Definition of polar star in English:

polar star

noun

Astronomy
  • A star at or close to a celestial pole, especially the Pole Star.

    ‘Alpha Draconis used to be the north polar star’
    • ‘The queen, however, is as constant as the polar star, and it is that continuity, stability and dignity which Britons are now celebrating.’
    • ‘These 38 stars were the 36 ‘fundamental stars’ of Maskelyne together with two further polar stars.’
    • ‘Yes, that's the first thing, like the Big Dipper here, the North polar star.’