The word "bit" has a rich etymological history dating back to Old English. It originated from the Old English words "bite" (meaning "act of biting") and "bita" (meaning "piece bitten off"). These words evolved from the Proto-Germanic *biton, which is also the source of similar words in other Germanic languages such as Old Saxon biti, Old Norse bit, and Old Frisian bite.

The meaning of "bit" as a small piece or fragment of anything dates back to around 1600. Over time, it acquired additional meanings: A short space of time (circa 1650s) A theatrical bit part (1909) A small coin (originally in the U.S. South and West Indies)

In computing, the term "bit" as an abbreviation for "binary digit" was coined in 1948 by U.S. computer pioneer John W. Tukey. This usage is distinct from the older meanings but shares the sense of a small unit.

The use of "bit" in phrases like "a bit smaller" stems from its general meaning of a small amount or degree. This usage predates the computing definition by centuries and is rooted in the word's original sense of a small piece or morsel.