Facsims  This stands for "facsimiles", an exact reproduction (usually photographic) of an older document. For example, a biography of a famous person might contain facsimiles of some of their letters, to show what their writing looked like.
First edition  The first print run or first impression of the first edition (as far as collectors are concerned). Bibliographers and booksellers commonly refer to second, third or more impressions or printings as first editions. They also name as first editions the first printing of the paperback edition of a hardback.
First Thus edition  Means not a true first edition, but something that is new. It may be revised, have a new introduction by the author or someone else, be the first publication in a new format, or first by another publisher. Omnibus editions come under this category too.
Free Endpaper  (also Front Free Endpaper ffep and Rear Free Endpaper rfep) - The first or last movable leaf of paper in a book aka Front or Rear Fly; often blank. Also see End paper.
frontispiece  Illustration which faces the title page.