roaming or wandering.

not assigned or restricted to any particular location, area, topic, etc.

a roving editor.

not assigned to any particular diplomatic post but having a special mission

a roving ambassador.

adjective

roaming , wandering , ambulatory , arrant , desultory , digressive , discursive , itinerant , migratory , mobile , nomadic , peregrine , peripatetic , vagrant

noun

aimless , ambulation , cursory , desultory , errant , itinerant , mobile , nomadic , nomadism , peregrination , peregrinity , rambling , straying , vagrancy , wandering