Random (9)
(Other definitions for arbitrary that I've seen before include "Based on random choice" , "lacking principles" , "Based on whims or irrelevancies" , "Capricious" .)
'random' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for haphazard that I've seen before include "Disorganised, random" , "Lacking order" , "Slapdash, slipshod" , "Careless or random" , "Lacking any obvious organisation" .)
'random' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sporadic that I've seen before include "infrequent" , "Occurring now and then - cop raids (anag)" , "Occurring here and there, like picadors" , "Occasional - intermittent" , "Occurring irregularly" .)