My first thought also was that
thermo is almost always used as a prefix, rather than a standalone adjective. But then I once thought that about
cyber, but eventually
came to accept it as a word that ought to be in our list. Likewise
uber.
It looks like the Collins is the only dictionary listing
thermo as a word in its own right.
Many of the usage examples I found are proper names, with a capital
T, especially a company called Thermo Fisher. Nevertheless, the word is being used in lower case for a variety of situations: "Motorcycle thermo gloves"; "thermo responsive gelatin polymer hydrogel"; "The start-up says that its built-in thermo alarm can wake up users gradually by changing the temperature of the bed"; "truck drivers are to have their temperature taken at designated weighbridges and border points using thermo guns provided by the Ministry of Health"; and so on. In most of these cases the more familiar word
thermal would probably have done just as well, but there's no law against using different words for the same thing.
One usage that had me puzzled was in book titles such as
Everyday Thermo Cooking,
Thermo-Struck: The Easiest Cookbook for All Thermo Appliances with Over 200 Amazing Recipes and - another cookbook -
Thermo Love, by
The Australian Women's Weekly. It seems the
thermo cooker is a new kind of kitchen appliance. But surely all cooking involves heat. The Australian
Choice website describes one of these products:
Billed as 10 appliances in one with 10 different speeds, the Aldi Stirling Thermo Cooker claims to mix, emulsify, knead, sauté, stir, puree, smoothie, crush, steam and mill and has an in-built scale to weigh out ingredients.
From what I can work out, these are cheaper alternatives to the branded Thermomix, but to evade trademark issues, they've dropped the "mix" from the product name.
Anyway, to cut to the chase,
thermo is creeping into the language, and I'll add it to our list as a rare word.