The list of common English words used by the Common Words view for exclusions is found in Contents/Resources/config/stoplist.txt within the Tinderbox app package. It can be overridden at app level by a customised user version in:
~/Library/Application Support/Tinderbox/stoplist.txt
Note this feature is essentially replaced by the use of the stoplist in the Built-in Hints container, if the latter is used.
The file is a plain text file, one word per line, all lower-case. The reason the word doesn't seems to appears twice is to allow for straight and typographic ('curly') variants of the apostrophe character. This is the default list:
about
after
also
because
been
corp
could
does
doesn
doesn't
doesn’t
each
even
from
have
here
indent
into
it's
it’s
just
last
like
many
might
more
most
much
only
other
over
perhaps
says
seem
seems
should
some
still
such
than
that
their
them
then
there
these
they
those
this
though
through
very
well
were
what
when
where
which
while
will
with
would
year
years
your
of
to
in
it
is
be
as
at
so
we
he
by
or
on
do
if
me
my
up
an
go
no
us
am
the
and
for
are
but
not
you
all
any
can
had
her
was
one
our
out
day
get
has
him
his
how
man
new
now
old
see
two
way
who
boy
did
its
let
put
say
she
too
use
don
ve
re
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