From the Greek 'sphugmos' - pulse.
Yes, I was as surprised as you to find out that the 'blood pressure measurer' that the doctor puts on your arm was called this. It is quite amusing (and possibly a little irritating) when relatively common items, or instantly recognisable ones in this case, have an obscure and difficult to pronounce name. This word is actually pronounced 'sfig-moh-muh-nom-i-ter', a pronunciation which is completely different to what came out of my mouth when I first read it. I'm not sure whether it makes me like the word more or less. In any case, a word with six consonants at the beginning does stand out from the crowd and any mispronunciation (good word) can be forgiven.
Usage: "Hey you, you're supposed to put the sphygmomanometer round your arm!"
