The number zero is often called "O" due to a combination of factors: brevity, visual similarity, and established convention.
Brevity and Efficiency
Saying "O" instead of "zero" is significantly shorter. As noted in several sources (Quora, Reddit, Stack Exchange), this time-saving aspect is a major contributing factor. The abbreviation saves time and effort, especially when reading long strings of numbers like phone numbers or coordinates. One source even suggests that this abbreviation saves significant time cumulatively (Quora).
Visual Similarity
The visual resemblance between the digit "0" and the letter "O" further contributes to the interchangeable use. This visual similarity (Reddit) makes it natural to substitute one for the other, especially in spoken communication where context often clarifies the meaning.
Established Convention
Over time, using "O" for zero has become a widely accepted convention, particularly in specific contexts like reading numbers aloud. This convention is reinforced through repeated use and acceptance in everyday communication, as seen in examples like automated responses reading numbers with multiple zeros as "OOOO O" (Reddit). While "zero" remains the standard written and sometimes spoken form, the use of "O" persists due to its established presence in casual speech.
The shortening of the word "zero" to "oh" is also explained by a process called clipping, which shortens longer words in a manner that is quite common in English (Quora). The final syllable of "zero" is identical to the word "oh," and clipping simplifies this down to one syllable. One source posits that this is due to a preference for fewer syllables (Feb 20, 2021).
In conclusion, the use of "O" for zero is a result of a combination of brevity, visual similarity and the evolution of language use.
