Meaning of Hubble's constant

Hub'ble's con'stant

Pronunciation: [key]
— Astron. Astron.
  1. the ratio of the recessional velocity of galaxies to their distance from the sun, with current measurements of its value ranging from 50 to 100 km/sec per megaparsec.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.