 Today, in surprisingly connected etymologies, we're going reptilian. Serpents don't give you herpes, but etymologically they should. Serpent comes from Latin serpents, snake, ultimately from the Proto-Indo-European root serp, to crawl creep. This root also leads to Greek hairpane, to creep, from which comes the Greek, Latin, and English word herpes, referring to a spreading skin condition. Also related is herpetology, the scientific study of reptiles and amphibians. Reptile, by the way, comes from a similar root, pi-rep, to creep, slink, from which comes Latin repera, to creep, and eventually English reptile. In terms of their biological classification, alligators and lizards aren't the same, etymologically they are. Lizard comes from Anglo-Norman-Lusard, and Old French, the sound. From Latin, the kertus, lizard, which came into Spanish as lagarto. This was used in the Spanish phrase, elagato de indias, the lizard of the indies, to refer to the alligator. And in English, this phrase became shortened to alagarto and eventually alligator, with the Spanish definite article becoming part of the word. The words basil and basilisk look a bit similar, but what does a herb have to do with a mythical reptilian monster? Turns out, it's a particularly royal etymology. The etymon behind both words is Greek basileus, king. Basil was so-called because it was used in making royal perfumes, and the basilisk was so-named because of the crown-like crest on its head, at least according to the Roman writer and naturalist Pliny. And finally, this one's not a reptile, but it crept in anyhow. Do frogs frolic? Etymologically they should. Frog comes from Old English froga, ultimately from the pie root preu to hop. This root also leads to Middle Dutch fro, leaping with joy, which comes into English as frolic. And if it keeps you leaping with joy to hear, the etymology of that other focus of herpetology, namely the amphibians, means literally leading a double life, those crafty frogs, coming from the Greek prefix amphi, both on both sides, also in the word amphitheater, ultimately from the pie root ambi around, plus the Greek word bios, life, as in biology, the study of life, from the pie root gway, to live. Originally, the words amphibian and amphibious could refer to anything combining two completely distinct or opposite conditions or qualities, with, for example, Joseph Addison using it in the 18th century to refer to clothing that we might now call unisex. And with the more general biological sense of any animal that lived both in water or on land, including crocodiles, beavers, and hippopotamia, before it was narrowed to its more specific modern sense. Thanks for watching. This is one in a series of occasional short videos about connected etymologies. To see more, you can also follow the endless knot on Twitter, Facebook, or Instagram.