What does the word axis mean?

Usage examples for axis

  1. Rapid as lightning, she springs forward till the measure recalling her to the place she left, she traces her orbit, like a planet, at the same time revolving on her axis. – Paris As It Was and As It Is by Francis W. Blagdon
  2. You're as true to the world as the world to its axis, But you chuckle to swear off your personal taxes. – Impertinent Poems by Edmund Vance Cooke