light as adjective (boring; grammar hounds only)

[Randy Allen Harris <raha -at- WATARTS -dot- UWATERLOO -dot- CA>]

When I said (responding to an earlier post):

> "Light" in "light wave" is clearly a modifier, though it's not an
> adjective.  Lots of nouns modify other nouns ("library hours", "school
> night", "user interface", etc.)

Robert Bononno asks

>Why wouldn't it be an adjective in this case, since it modifies another noun?

You're right that categories like "noun" and "adjective" aren't as rigid as
most people assume; nouns can modify other nouns ("bicycle seat"), for
instance, and adjectives can stand on their own ("there are reds under
every bed").  But in this instance, "light" is much more noun than it is an
adjective.  It hasn't changed lexical category, just function.

One way to tell is by morphology.  Most adjectives can form comparatives
and superlatives ("big", "bigger", "biggest"), nouns can't.  English does
have "lighter" and "lightest", of course, but they are formed from
different words (either the "light" of "not heavy" for weight, or the
"light" of "not dark" for colours).  Most nouns can be possessivized,
adjectives can't.  So, you can say "the light's effect was dazzling", but
not "the big's effect was dazzling".

And the old grade-school semantic test also works well:  "light" is a thing
here, not a property.  It is the substance which constitutes the wave, not
an attribute of it (compare "big wave" with "light wave" with "sound wave"
with "blue wave").

                       -------======= * =======-------
                              Randy Allen Harris
                           raha -at- watarts -dot- uwaterloo -dot- ca

   Rhetoric and Professional Writing, Department of English, University of
Waterloo, Waterloo ON N2L 3G1, CANADA; 519 885-1211, x5362; FAX: 519 884-8995