ON THE UNROLLING OF SPECIES

When Darwin discovered evolution, he didn't make the word up. It had already been in the English language for over 200 years, and meant "unroll", but was largely used in the sense of a popular military formation at the time. This came from the French cognate evolution, from the Latin word evolutionem, referring to the unrolling of a scroll or book. This is a conjugated form of the earlier word evolvere, "to unroll". Evolvere is a portmanteau of the barely-recognizable prefix ex-, meaning "out of" and the stem volvere, or "to roll".  Going further back, etymologists reconstruct the word as having derived from the Proto-Indo-European term which sounded something like wel and roughly meant "revolve". As Darwin used it, evolution was meant to describe how animals "unrolled" into being what they are today, and the rest is history.