a rule of transformational grammar that shifts a subordinate or modifying clause to the end of a sentence, as in changing That you sign the paper is necessary to It is necessary that you sign the paper.
Origin of extraposition
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
placement of something outside something else
transformational grammar a rule that moves embedded clauses out to the end of the main clause, converting, for example, A man who will help has just arrived into A man has just arrived who will help
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012