expository

from WordNet (r) 3.0 (2006)

expository
    adj 1: serving to expound or set forth; "clean expository
           writing" [syn: {expository}, {expositive}]

from The Collaborative International Dictionary of English v.0.48

Expository \Ex*pos"i*to*ry\, a.
   Pertaining to, or containing, exposition; serving to explain;
   explanatory; illustrative; exegetical.
   [1913 Webster]

         A glossary or expository index to the poetical writers.
                                                  --Johnson.
   Ex post facto