stick ‧ ler /ˈstɪklə $ -ər/ BrE AmE noun
[ Date: 1500-1600 ; Origin: stickle 'to argue about small points' (16-20 centuries) , from stightle 'to put in order' (13-15 centuries) , from Old English stihtan ]
be a stickler for detail/rules/accuracy etc to think that rules etc are very important and that other people should think so too