Learn English – What does “buggy” mean in “a hot, buggy August morning”

When this word is used by programmers, it is a synonym for "authoritative," "standard," or "official." That's meaning number 3 in the definition you quote.

It implies that there is one best, most official, most standard way to represent the string object and this is it.

For example sometimes things can be represented using a relative link or an absolute link. Relative might be something like ../foo.txt meaning "The file foo.txt in the folder above this one" while absolute is something like \\www.example.com\fileserver\share\foo.txt which can only refer to one file on the Internet. One might say that the latter name is canonical.

Last August will generally refer to the August of the previous calendar year.

If it is September 2010 and I mention what we did "last August", I almost certainly don't mean August 2010 (last month), but rather August 2009.

August of the same calendar year would generally be discussed by saying "in August". This applies whether it is June or October.

For example:

"Is Margaret coming in August?" (August is later in the year)

"That library book was due in August." (August has passed)

If your librarian tells you your book was due last August, you're going to be paying a much higher fine.