Dictionary.com
Thesaurus.com

spaceband

American  
[speys-band] / ˈspeɪsˌbænd /
Printing.
  1. a wedge-shaped piece of metal used in typecasting machines to adjust the space between words and to justify lines of type.


spaceband British  
/ ˈspeɪsˌbænd /

noun

  1. printing a device on a linecaster for evening up the spaces between words

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of spaceband

First recorded in 1900–05; space + band 2