What's the 'word' in parameter relpacement expansion?

[Han Pingtian <hanpt@xxxxxxxxxxxxxxxxxx>]

Hi,

I think

$ a='abc def'
$ print ${a:/def}

will get 'abc ', but it is 'abc def'. So it works just like ${a//#%def}?
The 'entire word' in the document is the same thing of 'entire string'?

In zshexpn:

... or `#%' in which case  the  pat‐
tern  must  match  the  entire string.

The  first `/' may be preceded by a `:', in which case the match
will only succeed if it matches the entire word


Thanks in advance!