- K
- "one thousand dollars," 1970s, from kilo-. As an indication of "strikeout" in baseball scorekeeping, first recorded c.1880, said to be from last letter of struck, since first letter was already being used as abbreviation for sacrifice. The invention of the scorecard symbols is attributed to newspaperman Henry Chadwick. K as a measure of capacity (esp. in computer memory) or number (esp. of salary), meaning "one thousand" is an abbrev. of kilo (q.v.).