Definition of "retrogression" [re•tro•gres•sion]

• The act or process of deteriorating or declining. (noun)
• Biology A return to a less complex or more primitive state or stage. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Though a retrogression is over this year as well as people had some -! more tim e to regulate their spending as well as selling habits, Black Friday 2009 will not be so big."
• "This system of neumes was in some ways a retrogression from the Greek letter system, for the neumes indicated neither definite pitches nor definite tone-lengths."
• "28 The rigidity with which London makes Fang's progression to civilization adhere to Buck's retrogression is intriguing, if unoriginal in the philosophical mishmash that serves as a backdrop to the episodes."