In baseball scorekeeping, a swinging strikeout is recorded as a K, or a K-S. A strikeout looking (where the batter does not swing at a pitch that the umpire then calls strike three) is often scored with a backwards K (ꓘ), and sometimes as a K-L, CK, or Kc (the 'c' for 'called' strike).

Why are strikeouts called KS?

A “K” is used to refer to a strikeout in baseball because the letter “S” was already used to score a sacrifice. So Henry Chadwick, the inventor of the box score, began using the letter “K” in the 1860s because it is the last letter of “struck”, which was the common term for a strikeout at the time.

Why are strikeouts K backwards?

Another reason the letter "K" is used is that it is made with 3 strokes of the pencil, symbolizing the 3 strikes for the strikeout. Chadwick also used a “backward K” when a batter strikes out looking or called out on the third strike because it isn't as common as striking out swinging.