C1 English Vocabulary List

oblige verb obsess verb obsession noun occasional adjective occurrence noun odds noun offering noun offspring noun operational adjective opt verb optical adjective optimism noun oral adjective organizational adjective orientation noun originate verb outbreak noun outing noun outlet noun outlook noun outrage noun outrage verb outsider noun overcrowding overlook verb overly adverb oversee verb overturn verb overwhelm verb overwhelming adjective pad noun parameter noun parental adjective parish noun parliamentary adjective partial adjective partially adverb passing noun passive adjective pastor noun patch noun patent noun pathway noun patrol noun patrol verb patron noun peak noun peasant noun peculiar adjective persist verb persistent adjective personable adjective personnel noun petition noun philosopher noun philosophical adjective photosynthesis physician noun pioneer noun pioneer verb