:
:help iw
iw "inner word", select [count] words (see |word|).
... word
:
A word consists of a sequence of letters, digits and underscores, or a
sequence of other non-blank characters, separated with white space (spaces,
tabs, <EOL>). This can be changed with the 'iskeyword' option. An empty line
is also considered to be a word.
... 'iskeyword'
:
'iskeyword' 'isk' string (Vim default for MS-DOS and Win32:
"@,48-57,_,128-167,224-235"
otherwise: "@,48-57,_,192-255"
Vi default: "@,48-57,_")
local to buffer
{not in Vi}
Keywords are used in searching and recognizing with many commands:
"w", "*", "[i", etc. It is also used for "\k" in a |pattern|. See
'isfname' for a description of the format of this option. For C
programs you could use "a-z,A-Z,48-57,_,.,-,>".
For a help file it is set to all non-blank printable characters except
'*', '"' and '|' (so that CTRL-] on a command finds the help for that
command).
'V iWは単語全体を選択する – tinmarino