shift key

WordReference Random House Unabridged Dictionary of American English © 2025

shift′ key′, 

1. Computing a typewriter key that determines whether characters are printed in upper or lower case and controls the printing of numbers and symbols.
2. Computing a key that performs the same functions as on a typewriter keyboard and also controls other functions, depending on the program:
   To print a file, depress the shift key and a function key.
• 1900–05