Distance in degrees from the prime meridian (9)
I believe the answer is:
longitude
I believe this is a double definition.
'distance in degrees' is the first definition.
(I've seen this before)
'the prime meridian' is the second definition.
(thesaurus)
'from' is the link.
(Other definitions for longitude that I've seen before include "this helps define our position" , "Distance in degrees" , "Imaginary circles of distance east or west" , "Distance east or west of the Greenwich meridian" , "Word often paired with latitude" .)