On-ramping refers to the process of re-entering the workforce after taking a career break. This can be the result of needing to take care of family, taking a break professionally to explore other passions, or many other reasons. It is paired with the term "off-ramping", or exiting the workforce as a temporary career break.
The Hidden Brain Drain, a taskforce led by economist Sylvia Ann Hewlett, defined the term as
A study by the Center for Work-Life Policy found that more than 90 percent of those women who off-ramp eventually wish to on-ramp back into the work force.
The term appears as early as 2005, reaching public mention on NPR that same year. The term appears in articles in publications such as the Wall Street Journal by 2006, and by 2008 appears in formal training materials for organizations such as the American Institute of Certified Public Accountants as a business best practice.
References marketplace.publicradio.org/display/web/2005/12/09/off_ramping/ Sue Shellenbarger of the Wall Street Journal writes about the efforts of Lehman Bros and other Employers to help high achieving women reenter the workforce. "We Can Stop the Female Brain Drain," by Sylvia Ann Hewlett, March 6, 2005 http://www.aicpa.org/download/career/wofi/0666-331_WLWIECs_Off-Ramping_Program.pdf