[1] : The Collaborative International Dictionary of English v.0.48

quiddity \quid"dity\, n.; pl. quiddities. ll. quidditas, fr.
   l. quid what, neut. of quis who, akin to e. who: cf. f.
   quiddit'e.
   1. the essence, nature, or distinctive peculiarity, of a
      thing; that which answers the question, quid est? or, what
      is it? " the degree of nullity and quiddity." --bacon.
      1913 webster

            the quiddity or characteristic difference of poetry
            as distinguished from prose.          --de quincey.
      1913 webster

   2. a trifling nicety; a cavil; a quibble.
      1913 webster

            we laugh at the quiddities of those writers now.
                                                  --coleridge.
      1913 webster
see also:
quiddities 

Quiddities >> Q Words
Quiddities, definition of term: Quiddities
quiddities_pag1.html