What is the role or the meaning of “less” and “of” in “it's less of a mouthful than 'Henrietta'”?In “I've always called myself...

In "it's less of a mouthful than 'Henrietta',” the word
less functions as a
determiner in the noun phrase "less of a mouthful." title="Determiner: Oxford Advanced Learner Dictionary Online"
href="http://www.oxfordadvancedlearnersdictionary.com/dictionary/determiner">Oxford
Dictionary Online defines a determiner as "a word
such as the, some, my, etc. that comes before a noun to show how
the noun is being used." You can see that less is similar in nature
to the example some (note the etc. in Oxford's
definition indicating an expanded list of possible determiners). In addition,
less in the comparative less than cannot be
analyzed in isolation because, in this comparative context, it is part of a formula for
comparison, that being less than. Oxford gives patterns for it's
use as (1) less of a something than something and (2) in
less than something. Further, in this usage,
than functions as a
preposition (Oxford).

The
comparative phrase "less of a mouthful than" fits the href="http://www.oxfordadvancedlearnersdictionary.com/dictionary/less+than#less_1">Oxford
pattern less of something than something. The
role of
less is to describe the type of
comparison in the pattern less of something to more or something
else. Its meaning is that of a
determiner in a noun phrase; it shows how the noun is being
used. In this case, the noun mouthful is being used as the
point of (or the origin of) a comparison to another thing. The comparison of the noun to
another thing gives clarity on how to perceive, understand, or think about the other
thing. In this case, the noun mouthful, in relation to Henny, gives
clarity to how to think about Henrietta: it is harder to say; it is too long to say; it
is too formal to say; etc.

In "it's less of a mouthful than
'Henrietta',” the word of functions as
a preposition in the noun phrase "less of a mouthful."
href="http://dictionary.cambridge.org/search/british/?q=of&x=0&y=0">Cambridge
Dictionary Online defines of exclusively as a preposition
and gives more than a dozen meanings for its use. These include its meanings indicating
possession, amount, position, made of, judgement, relating to, done by, felt by,
comparing, and many more.

The
meaning that pertains to
of in "it's less of a mouthful than
'Henrietta'” is that of amount. It is comparing the figurative amount of
Henny--remember, we are working with the figurative idiom "less of a mouthful" since you
cannot have a literal mouthful of Henny, either the name or the person--to the
figurative amount of Henrietta--nor can you have a literal mouthful of Henrietta, name
or person. So the role of plays in
"less of a mouthful" is that of a connecting preposition.
href="http://www.ldoceonline.com/dictionary/preposition">Longman,
Cambridge, and Oxford Dictionaries define a preposition as a word before a noun (or a
pronoun or a gerund) that shows its relationship or
connection to another word. These relationships and connections pertain
to time, location, direction, amount, place, position, and
method.

Regarding your
suggestions as to the syntactical analysis of less
and of, first, although
Cambridge Dictionary defines less as having a pronoun function,
here less is clearly used as a
determiner in a noun phrase ("less of a mouthful" noun
phrase: determiner + preposition + article + head noun). So your suggestion that
less is a pronoun is not correct. None
of your examples are syntactically like the noun phrase "less of a mouthful."
Second, you have seen that Cambridge Dictionary defines
of only, solely, as a preposition. Oxford and Longman agree. So
your suggestion that of is an
adjective in "less of a mouthful" is not correct. Each of
your examples is syntactically very different from "less of a
mouthful."