Noun

1. A quadrangle (courtyard).
2. A quadruplet (infant).
3. short for quadrilateral
4. A quadriceps muscle.
5. Four shots of espresso.
6. A quad bike.

Etymology 2

Noun

1. A blank metal block used to fill short lines of type.
   • 1853, Charles Dickens, “Household Words”, n 160 (April 16), p 148:

      “Quadrats, sir. We call 'em quads.” . . . Quads are the spaces left between the paragraphs that come white on the paper. If you look here, at this page that is set-up, you will see that they are deeper than the spaces left between the words and letters—regular little trenches.

   • 1979, Marshall Lee, Bookmaking, p 110:

     Horizontal spacing is further divided into multiples and fractions of the em. The multiples are called quads. The fractions are called spaces.

   • 2005, Phil Baines and Andrew Haslam, Type & Typography, 2nd ed, p 91:

     Other larger spaces – known as quads – were used to space out lines.

2. A joke used to fill long days of setting type.
3. A keyboard command which aligns text with the left or right margin, or centred between them. In combination, as quad left, quad right, or quad centre.

Verb

1. To fill spaces in a line of type with quads. Also quad out.
2. To align text with the left or right margin, or centre it.