1) PO device 2) PO instrument 3) PO machine 4) PO stamp 5) Antique dealer, at times 6) Antiques Roadshow expert 7) Appointment maker 8) Archaeologist, at times 9) Carbon-14 10) Circulation desk gadget 11) Computer, at times 12) Dendro- chronologist 13) Library device 14) Library gadget 15) Library gizmo 
• (n.) One who dates.
Dat'er noun One who dates.