three dimensions, three-dimensional

triangular prism

three years; the third year / (education) the third school year / (figuratively) a long period of time, several years

three years; triennial / three years old

three years of age, three years old

You should treasure every encounter, for it will never recur.

vicissitudes, the way that the world or a person prospers one day and declines the next

dotting the i's and crossing the t's

successive series of questions and responses

an order of merit higher than first class in the Japanese honors system