This is the 3530th most frequent German word.
lewis
The word "Lewis" is not German; it is typically a name in English. It does not have a specific definition in the German language.
In this sentence, 'Lewis' is used as a proper noun referring to a person's name.
Lewis ist ein sehr kluger Mann.
Lewis is a very clever man.
Here, 'Lewis' is part of a technical term in chemistry, referring to a type of acid (derived from Gilbert N. Lewis).
Die Lewis-Säure reagiert mit der Base.
The Lewis acid reacts with the base.
In this example, 'Lewis' is the name of the author credited with writing the book.