Wordnet 3.0
NOUN (1)
1. 
 a blank leaf inserted between the leaves of a book; 
The Collaborative International Dictionary of English v.0.48:
Interleaf \In"ter*leaf`\, n.; pl. Interleaves. [See
   Interleave.]
   A leaf inserted between other leaves; a blank leaf inserted,
   as in a book.
   [1913 Webster]
WordNet (r) 3.0 (2006):
interleaf
    n 1: a blank leaf inserted between the leaves of a book
The Free On-line Dictionary of Computing (30 December 2018):
Interleaf
   A document preparation system for Sun, VAX, Apollo and
   other workstations.
   (1994-11-09)