This question is far too old and my notes far too scanty to give you any reliable context for how it came up. But I can make a few guesses. Since what notes I have on this topic date from right about the time The Five-Year-Old went in for her last well-child exam, it could be that The Five-Year-Old was questioning why we had to celebrate her birthday by giving her quite so many shots — a query that would naturally have launched a discussion of the various diseases. On the other hand, she could have simply asked me why I have a scar where my glasses sit on my nose.
Come to think of it, there are probably as many ways this question could have come up as there are answers to this question. Which means you get to pick your favorite:
Option #1: The name comes from cicer, the Latin word for chickpea. Back in the day, folks decided that chickenpox blisters look like/are the same size as chickpeas. Pox or pocks being an ancient term for any disease that causes boils and blisters to break out on the skin, it was only logical to put cicer and pox together to come up with chickenpox. (Via Reader’s Digest and KidsHealth)
Option #2: The name comes from gican, the Old English word for itch. Also from the Reader’s Digest comes the idea that chickenpox was named for its other dominant symptom — extreme itchiness. Pair the Old English word for itch, gican, with the Old English pox and you’ve got gicanpox. Really not hard to imagine that becoming corrupted into chickenpox, is it? (Via Reader’s Digest)
Option #3: Because “chicken” also means weak or timid. Smallpox is a terrible disease. The virus behind chicken pox, varicella, is highly infectious and itchy, but it’s not nearly as terrible. So to distinguish it from the more virulent smallpox, doctors and scientists took to calling this weaker form of the pox chickenpox. (From The Straight Dope)
Option #4: The obligatory chicken theory. Once upon a time folks thought the pustules caused by chickenpox looked like the peck marks left by chickens. (Via KidsHealth)
So many theories. How to choose the best one? Let’s see what the Shorter OED has to say.
Chickenpox [perh. from the mildness of the infection] a mild eruptive disease due to viral infection, chiefly affecting children; also called varicella
Looks like we’ll be going with Option #3. Scientists called this disease chickenpox because it just isn’t as awful as the smallpox.
- Chickenpox Cases Fall 80% Over Decade (nlm.nih.gov)
- Chickenpox Outbreak Hits Homer, Soldotna (alaskapublic.org)
- What is Chickenpox? Causes, Symptoms & Treatment (livescience.com)
- “Why is it called that?”: The Dragon & Dragonfly Edition (caterpickles.com)