Update : March 20, 2020
Children are not shy and tend to pick up words — often in multiple languages — quickly and easily.
As people grow older, most tend to live within their comfort zone. Such people probably add only 10 – 20 new words a year.
Necessity and Assimilation
My friend’s younger brother and sister are medical doctors from Burma who did not know Chinese. They chose to work in Taiwan. After working there for a year, they felt at ease communicating in Chinese. Assimilation helps improve one’s vocabulary.
During the Japanese occupation, several Burmese mastered Japanese quickly.
Improving one’s vocabulary
To expand or refine one’s vocabulary, one could and should take extra effort.
In our younger days, we learned from a Reader’s Digest section “It pays to increase your word power” by Wilfred Funk, co-compiler of the Funk and Wagnall’s dictionary.
We studied Vocabulary Books which cover a lesson a day for three to six weeks.
With the rise of Broadcasting and Internet, it is easy to grow one’s vocabulary.
One can subscribe to Merriam Webster for “Word of the Day“.
One can listen to “Word for the Wise” by NPR (National Public Radio).