It's rather very interesting because at the time of Jesus girls were married young; it's believed that Mary was only 15 or 16 years old.Sorry. I didn't see this post.
There are several things to consider when discussing the meaning of a word.
the culture in which the word is used, (Modern western, ancient Chinese, Druidic Britain)
the language itself (English, Urdu, Swahili, Japanese, etc.)
The time of use. (Modern, middle ages, industrial, pre-industrial, stone age, bronze age, iron age, Middle ages)
All of these influence the meaning of a word.
Pederasty is a modern English word which refers to adults having sex with children.
The definition of "adult" and "child" varies from culture to culture.
In modern USA, (and in most of Western Europs, as far as I am aware) our legal definition of "adult" includes being 18 years of age or older while a "child" is under the age of 18.
Other cultures have different views and many girls are married by the time they are 14 to 16 to men in their 20's. (Who are able to support a wife and family.)
Hope that helps
The Didache says NOT to commit pederasty which means that they did not believe young girls should be married to older men, unless, of course, they were agreed to it.
This is definitely a step up from even practices of today in some countries where young girls are promised to older men; making their lives miserable many times because they do not care for the person. (and may even love someone else).