useless trivia: What Word Means: In The Sense Of - As Understood Or Defined By?

Questions

On This Day In January 1968 - The cost of a U.S. first class ______ was raised to 6 cents.?

On This Day In January 1975 - ______ agreed to raise crude oil prices by 10%, which began a time of world economic inflation.?

On This Day In January 1979 - ______ forces captured the Cambodian capital of Phnom Penh, overthrowing the Khmer Rouge government.?

On This Day In January 1989 - Crown Prince Akihito became the ______ of Japan following the death of his father, Emperor Hirohito.?

On This Day In January 1990 - The Leaning ______ of Pisa was closed to the public. The accelerated rate of "leaning" raised fears for the safety of its visitors.?