The Secret Life of Words: How English Became English
This is a book for word mavens, of whom I am one. Does it make your day to discover that the Russian word for a train station (vokzal) derives from a specific train station (Vauxhall) in South London? Do you cherish the knowledge that "robot" is etymologically related to the German "arbeit"? Then The Secret Life of Words is for you.
TSLoW is structured as a chrono-thematic journey through English. It purports to demonstrate how English acquired vocabulary from other language in response to specific circumstances, and to be fair it does some of that.
But, really, it's all about the words.
TSLoW is chatty. It's digressive. It's full of largely useless but enjoyable facts--no human being could possibly remember any appreciable fraction of the etymologies herein. Naturally, I liked it a lot.
Good crossover reads include John McWhorter's Our Magnificent Bastard Tongue and Bill Bryson's The Mother Tongue: English and How It Got That Way. The first is more learned, but very readable; it's a bit of a favorite of mine. The second is somewhat unreliable--take it with a pinch of salt--but entertaining.