In a Flap

You've probably noticed that a striking, almost astonishing, number of words suggesting delicacy and airiness begin with the letter "f-", and particularly "fl-": feather, float, flutter, flit, flurry, frill, fluff, fly, flow, and on and on. Some of them share a meaning, or at least a feeling, because they're etymologically related: "flow" and "flutter" are derived from Indo-European "pleu-" (which is also the source of "pulmonary").

"Feather", though, is what got me started, and it's the word that most interests me of the bunch. We got it from the Germanic side of the family: the modern German word is "Feder". "Feather" is also traceable back to Indo-European: the root in this instance is "peth-", "to rush", "to fly". The number of words that stem from this root is in itself astonishing. First and foremost after "feather" is "pen", which was once made from feathers; this derives from the Latin version of "peth-", "pinna". From "pinna" we also get "pinnacle", meaning "little feather"--originally a little turret on a roof, and later the highest point of anything, from a mountain to an achievement. "Pin", predictably, is from the same root (making "pinfeather" something of a tautology), as is the flipper-footed "pinniped" and the hanging "pennant".

Then if we take off in another direction, an early extended sense of "peth-" that manifested in Latin as "petere" meaning "to seek" (that is, "to rush at"), we run into such words as "compete" (literally "to seek with", which is to say "to seek to win something alongside someone"), "repeat" ("to seek again"), "appetite" ("a striving after something"), and "perpetual" ("ever-seeking").

One more word from this fecund womb: the sense of "rush" gave the Greeks the word "potamos", a river which rushes, and that in turn gave them the word for the river-horse we know as a hippopotamus.