Q: Why do the words “pneumonia” and “pneumatic” start with a “p” even though we don’t pronounce the “p”?
A: The noun “pneumonia” and the adjective “pneumatic” are spelled that way because the Greek and Latin originals started with “p.”
The first is from the Greek word pneumonia, which was adopted into medieval Latin and then into English in 1603.
The second is from the Greek word pneumatikos, which became pneumaticus (having to do with wind or breath) in Latin and finally “pneumatic” in English in the 1600s.
The “p” is silent in English, though it is pronounced in modern Greek and probably was in classical Greek as well.
All this reminds me of a 1965 interview in which Vladimir Nabokov was asked how to pronounce the last name of the title character of his novel Pnin. Here’s Nabokov’s answer:
“The ‘p’ is sounded, that’s all. But since the ‘p’ is mute in English words starting with ‘pn,’ one is prone to insert a supporting ‘uh’ sound – ‘Puh-nin’ – which is wrong. To get the ‘pn’ right, try the combination ‘Up North’ or still better ‘Up, Nina!’ – leaving out the initial ‘u.’ “