What is the keyword used to designate a semantic field specific to a certain period of time?

When the words 'bowler hat, shilling, bobby...' appear in a text, they tend to show that it is from a certain time period. What's the word used to describe this sort of giveaway? It's kind of similar to semantic field but surely there's a key word more specific to this concept?

I don't know of a specific term but you can say that certain words date a text (from the American Heritage Dictionary, courtesy of wordnik.com):

date
transitive v. To determine the date of: date a fossil.
transitive v. To betray the age of: Pictures of old cars date the book.

So, in your example, you could say

The presence of words like shilling and bowler hat¹ date the text to the 19th century².

¹_{But not bobby which is still quite commonly used today.}
²_{Or, at any rate, before the 1971 decimalization.}