All caps

adjective; clipping
Writing that is solely written in uppercase, with no use of lowercase letters in the alphabet. Used to communicate intense emotion, emphasis, or importance of a word, phrase, or sentence in text format. Often likened to yelling, but in a text format. Using all capital letters is primarily reserved for online posts or messages among peers.
Used to describe a manner of typing or writing that primarily exists in a colloquial setting. Using all uppercase letters can be seen as informal or even aggressive, as if one were yelling. The use of the word is primarily likewise restricted to colloquial settings. It is possible this clipping came to be due to it being the clipping visible on the computer keyboard for the “Caps Lock”, which locks the keyboard as uppercase. “Caps Lock” is a clipping that was created to conserve space on the keyboard. Likewise, “all caps” conserves time and limits the typing necessary. Because all caps refers to written language, it is likely that “all caps” itself originated in written language, and only later came to be used orally, as well. Uppercase is used for names of people, places, and the beginnings of sentences. Uppercase is also bigger in size. Both of these confer greater importance on capital letters, so using all caps emphasizes what is being said. This is also likely why there appears to be no “all lows” or similar for only using lowercase letters.
Etymology : “All caps” is a compound of “all” and “caps”. “Caps” is a clipping of “capitals”, which is in turn a clipping of the compound “capital letters”. “Capital” and “letters” were compounded to indicate a type of letter, one that is uppercased.
Source : “thank you for your comments (the screaming, the anger, the all caps despair) on the last ch.” 2018-11-05 Context: Author of fanfiction thanking those who commented on their piece
Last modified: 16 December 2019