the first shell of electrons surrounding the nucleus of an atom and containing, when filled, two electrons having principal quantum number 1.
1. one thousand pounds per square inch.
Knowledge Systems Laboratory
1. Keyboard Send Receive. 2. Kendall Square Research. (1995-11-23)
noun, Astronomy. 1. a relatively cool, orange-to-red star, as Aldebaran or Arcturus, having a surface temperature between 3500 and 5000 K and an absorption spectrum with strong lines of calcium and many neutral metals.