Capital letter “L” in Oxford English Dictionary entry

Question

I just started Snow Crash by Neal Stephenson and am wondering what the “L.” in the first line of the definition for “virus” means. I checked the online Oxford English Dictionary commonly used abbreviations page but found nothing meaningful.

As a side question, why are there brackets around that definition? Was Stephenson adding his own definition?

Answer 1

The L stands for Latin, which is the origin of the English word. The brackets around that definition are used to separate the Latin definition from the English definition.