some abbreviations go back to the telegraph age, when you paid for every word you sent. Some go back even further, to the Quipu system of the Incas (talking knots).
Many words that were two separate words, like “to day” became one word, today. Western Union would count the words, and disallow words it thought were illegitimate compound words. The newspapers, which were very large users of telegraph services (think foreign correspondents) would show Western Union that these were indeed single words, just look at what they’re printing in the newspaper.
this goes back:
ASAP – as soon as possible.
SAP – soon as possible.
SAPIEST – sooner than soon as possible.