implacable(adamant; immovable, see also: adamant; immovable) adjective [UK: ɪm.ˈplæk.əb.l̩] [US: ˌɪm.ˈplæk.əb.l̩]John is implacable. = John är enveten.
recalcitrant(hard to deal with or operate) adjective [UK: rɪˈk.æl.sɪ.trənt] [US: rɪˈk.æl.sə.trənt]