Above is a picture of a single song of a Chuck-will's-widow. The controls on the left play this one song at half speed. The controls on the right play today's entire cut. Let's use these tools to better understand how someone came up with this transliteration of the bird's song, and thereby its onomatopoeic name. If you look at the dark tracings on the figure, you can easily make out the three "words" of the name. The downslur on the left is the "chuck," and the "M-shaped" phrase on the right is "widow." Trouble is, the middle phrase looks very similar to the right one, leading to "Chuck-widow-widow." In fact, that's exactly how Pieplow transliterates this sound. So, where does "will's" come from? Perhaps some raconteur sitting on a front porch in the days before radio invoked a distant bird sound to introduce a yarn about a man named Will, and the wife who survived him Or maybe that little note, right before the second "widow," makes the two phrases different enough to pronounce differently. You can hear it if you listen for it. Now click the controls and see what you think the bird is saying.
When I brought up monotony with regard to the singing of the Red-eyed Vireo I said that the capgrimulgids are the kings of monotony. Well, here you have an example. Partly it is a function of their persistence, which they share with the vireo. Don Kroodsma has a lot to say about this in The Singing Life of Birds.
And finally, having taken apart the English name of a caprimulgid, what about that scientific name? It has been translated into English as "goatsucker," which, along with "nightjar," is often used for the entire family. These birds may be seen fluttering up from the ground at night. In fact they are catching unsuspecting flying insects, but the ancients apparently didn't think of the insect option, and hypothesized that they used the fluttering maneuver to poach milk from nanny goats. So much for Occam's Razor.