Thereof, therein

Hello,

         Sometimes, I find the words, "thereof", "therein" at the end of the sentences. What do they mean and how can I use them? Is it common to use these words? Thank you very much.

Best Regards,

np36

Good question!

Thereof & therein are both adverbs. Thereof means "of that" or "from that cause," while therein means "in that place or time." These words are not very often used; they're a bit old fashioned. However, it's fairly common to hear the phrase "lack thereof," as in, "I'm depressed about my love life—or lack thereof."  

I hope that answers your question!  

Make sure you aren't confusing"lack" with "luck." "Lack" means something is missing or absent. So when I say, "I'm depressed about my love life—or lack thereof," I mean that what I'm really depressed about is the fact that I don't HAVE a love life.