herein (adv.): in this

There’s a peculiar class of words in English that combine shorter adverbs, prepositions, and conjunctions into longer ones. They may be most often found in legal jargon, but they’re used in a fair amount of logical or self-referential writing, though rarely in speech. They range from the simple and common (“whereas”) to the more sophisticated (“notwithstanding”) to the positively obscure (“heretofore”).

I find “herein” especially interesting because it combines to form longer strings, and because it is amenable to that particularly English method of prefix specificity that gives us then/when, what/that, and here/there/where. (The origin of this method appears to be rooted in the trinity he/that/who describing people rather than places.) This method yields such words as:

herein
therein
wherein
hereinafter
thereinafter
hereinabove
hereinbelow
hereinbefore
thereinbefore
hereinto
thereinto
whereinto
whereinsoever

Most of these words are contrived and silly, of course, and it’s only because I spend entirely too much time around lawyers that I find myself dropping phrases like “therein contained” into casual conversation.