If meaning of a word able to vary by sentence, what does it mean by alone?

Question

So I mean there are too many words which is multiple meaning in English. And these sentences are able to vary by sentence. For example:

The house by the tree.

"by" means "next to" or "near"

This book was written by a popular author.

"by" means "product of".

What does these words mean when we use them by alone? When does "by, as, about, so" mean different? What is the basic meanings of these words?

Answer 1

In many languages there are many words whose meaning depends on the context in which they occur.

These words do not have a single "basic meaning". A good dictionary will tell you when there are several meanings, and illustrate each with a sentence or two. Your examples demonstrate that for "by" in English. Sometimes the several meanings are related, sometimes not.

That is part of what makes learning a new language difficult.

Answer 2

Some English words may have many different meanings, depending on context. For example:

• She is running the race.
• The car is running out of gas.
• His nose is running.
• She is running for office.
• The producer is running the show.

Another example:

• The gas is unionized. [No atoms have gained or lost electrons.]
• The company is unionized. [Employees have joined together to form a union.]

That is why English dictionaries give a list of definitions. No, English is not an easy language to learn. Perhaps Esperanto or other synthetic language would be easier to learn, but it is not very widely used.