4. On "word meaning" my preference is to think about sentence meaning.
Here it will be clearer that words, absent from a sentence, do not comprise
a completed meaning. They have aspects which are defined, ofcourse, but
these definitions only form part of a system of meaning which is derived
from the synthesis of all the words in a sentence (and wider contexts). To
ascribe a "completed" "word meaning" to "all those meanings implied by all
possible sentences in which this word can be used" would be like trying to
put the whole world in a shoe box, because the system of constraints that
comprises all of the sentences is greater than those that comprise the
word. Word meaning in this light is then a different genus of meaning to
sentence meaning, it is a derivative of sentence meaning just as
acceleration is the derivative of velocity (with time), hence they are not
of the same type (genus). I suspect that the fuzziness to which you refer
is partially the confusion of types of meaning. If instead of this
elaborate interpretation of word meaning that encompasses all of the
ambiguities that arise of its use in a sentence, we refer to "word meaning"
as simply the known system of constraints that are the conventional
definition of a word and that participate in sentence meaning, then we have
a more tractable account of word usage that is also (I believe) more in
line with scientific concepts, hence word and concept align better.
Huw