New words are constantly being added to the Merriam-Webster dictionary, because new words are constantly being invented. For example, the words "binge-watch," "photobomb," and "humblebrag" are recent additions to the English language, therefore, they're recent additions to the dictionary (whether we like it or not). Whereas words like "forehoof" and "rheumatic fever" were in introduced in 1726. Words are clearly products of the time we're living in.
Merriam-Webster has a Time Traveler section on its website that lists the first known use dates of words based on the year. So, let's say you want to see the words that were born the same year as you (because that's fun). If you select the year you were born (or any year you're interested in), a list of words that were first used in print that year will populate.
You can look at words based on the specific years they came about starting in 2010, with words like "hashtag" and "bucket list," all the way back to before the 12th century when words like "cloth," "marshmallow," and "Jesus" made their way into vocabulary.
Here's a look at some words from 1953
Here are some from 1983:
And here are some from 1996:
Looking back at words that were popular in decades past is either a history lesson or a walk down memory lane, but interesting and fun, nonetheless.