I'd be inclined to cut this teacher a bit of slack though. My son has a PhD in Post-colonial literature, and his studies involve thinking about the practices during the colonial period that led to the attitudes and features common to post-colonial thinking. 'Post' does mean 'after' of course, but an academic can't shut his/her eyes to what came first.
So, if you like, the teacher was 'wrong'. But they were saying something important about their area of study.
b
For reasons I don’t know, the U.S. uses the abbreviations B.C. and A.D. to fix a timeline to history, specifically around the birth of Jesus Christ. While “B.C.” is an English abbreviation for “Before Christ”, the “A.D.” abbreviation is inexplicably Medieval Latin “Anno Domini”, for “In the year of the Lord”. Well, it’s common for the uneducated to think (and not surprisingly so) that “A.D.” means “After Death”. If this were true, we’d be missing some 33 years!
The meaning of 'post war' or 'post-war' seems to be partly culturally dependant. As a person who grew up in Australia, having been born in 1944, I was conditioned through the use of this term in my environment to regard the phrase as referring to the period after the Second World War, from 1946 on possibly into the late-fifties or even early sixties. It is a relative term. For people from other cultures, it could refer to a period (often of political and material reconstruction ) following a localised war, e.g., the post-war or 'post-Milosevic' period following the conflicts in the Balkans. Although Vietnamese may refer to the period following the victory of the North over the South as 'post war', for example, I have not heard Australians referring to this period generally as the 'post war' period. They just say 'after the Vietnam war'. The period between the First and Second World Wars is sometimes referred to as just that: 'between the wars'. But one could only say that more or less after the Second World War. I'm not sure if the phrase 'post war' was commonly used in the period after the First World War and before the commencement of the Second World War. Interesting that Roman writers referring to the period before the outbreak of the Carthaginian wars called it the 'antebellum', literally 'before the war'. 'antebellum' has been used by some writers, I think, in reference to other before war periods, e.g., before the Civil War in the States. It's a fascinating question. Jim Daly.