- a horizontal bar on a typewriter keyboard that is depressed in order to resume typing one space to the right.
- a horizontal bar on a computer keyboard that is depressed in order to move the cursor one space to the right or, often, to perform some function in a program.
Origin of space bar
First recorded in 1885–90
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018