The “Con” in both is from a Latin root meaning together.

The “test” in contest is from Latin testis, meaning “witness”, from a root meaning “three” (as in, a third party).

The word test is from Latin testum meaning earthen pot, because metals could be tested for quality by melting them in such a pot.

Etymology is super interesting to me.

I always thought that the word “island” was just short for “isolated land” – There has to be some reason there’s an ‘s’ in there right?. But some etymologist told me it didn’t come to be in that manner.