Definition from Wiktionary, the free dictionary
mid-twentieth (not comparable)
- Usually used before century to indicate the middle part of the 20th Century, which could refer to events in the 1940s, the 1950s or the 1960s. However, in architecture, preservation, and real estate, it is commonly being used to refer to the period after World War II to the mid-1970s.
- Since the mid-twentieth century, the exchange of Orders has become less personal and more formal and diplomatic.