I was explaining to the kids the difference between the prefixes “hypo-” meaning “below” or “under,” and “hyper-” meaning “over.” My kids are used to this sort of thing, and will grow up assuming that everybody’s parents give long lectures about etymologies.

It came up because Old Kid was making fun of his little brother for saying “hyperthermia” instead of “hypothermia.” I pointed out that those are both words. But I had trouble coming up with examples of other words that have both “hypo-” and “hyper-” variations that are commonly used (and not just by doctors and chemists). You can be hyperactive, but not hypoactive. You can be a hypochondriac, but I’ve never heard of a hyperchondriac.

We thought about the word “hypothetical.” Can something be hyperthetical? I hypothesized that the “thet” part of the word meant “truth” and was related to the “taut” in tautology.  So if something were “hyperthetical,” maybe it would be EXTREMELY true. And “hypothetical” could mean just below the truth, something that we think could be true but it hasn’t been proven.

According to the Online Etymology Dictionary, the word “hypothesis” is derived from “thesis”: “a placing, proposition” (from reduplicated form of PIE root *dhe- “to set, put”) . PIE means Proto-Indo-European.  The “dhe-” root is credited for all kinds of words from “malefactor” to “salmagundi.” I imagine this is similar to how humans are related to shrimp.

Tautology, on the other hand, comes from Greek root words meaning “the same” (tauto) and “saying” (logos). So my hypothesis was not hyperthetical.