* Mathematical Opposite: The mathematical opposite of 1855 is -1855. This is the additive inverse, where adding the two numbers results in zero.
* Chronological Opposite: If you're thinking about the opposite of the year 1855, you could consider its distance from a specific point in time. For example, the opposite of 1855 relative to the year 2023 would be 2023 - 1855 = 168 years later.
* Conceptual Opposite: There isn't really a clear conceptual opposite of the year 1855. It's a specific point in time, and the concept of an "opposite" doesn't easily apply.
To provide a more accurate answer, please clarify what kind of "opposite" you're looking for.