Definition - What does Caps Lock mean?
Caps Lock is a key on a computer keyboard that allows users to generate letters in uppercase once activated, as in "SAMPLE," without holding down the Shift key. It is a toggle key and can be found on the left side of a computer keyboard below the Tab key. To activate the key, the user has to press it once and the button locks on the Caps Lock feature, making all subsequent typed letters the capital form. The user needs only to press it again to turn the Caps Lock feature off.
Techopedia explains Caps Lock
The Caps Lock key is a modified version of the Shift Lock key found on mechanical typewriters. Generally, mechanical typewriters require more force to press keys, making it difficult to press down the Shift key continuously, especially when there are more than two letters that need to be typed.
The introduction of the Shift Lock key on mechanical typewriters aided not only those who frequently used the Shift key, but also those who are disabled and unable to hold down more than one key at a time. For the computer keyboard, it was simply decided to make the Shift lock key the Caps Lock key instead.