PDA may stand for:

• personal digital assistant, a type of handheld computer.
• public display of affection, an area of study within social psychology
• patent ductus arteriosus, a medical term referring to a congenital defect where the ductus arteriosus fails to close after birth
• pushdown automaton, a type of abstract device in automata theory
• the chemicals polydiacetylenes
• the Polyurea Development Association [1] (see also polyurea)