YD stands for;
YD Yard
YD Young Democrats
YD Younger Dryas (prehistoric climate period)
YD Year-to-Date
YD Year Date (date on a stamp; philately)
YD Floating Crane (Non Self-Propelled)
YD Yankee Division (WWI; infantry division from New England)
YD Yaw Damper
YD District Derrick, Floating (US Navy)
YD