Why do you have to add the letter "H" after the letter "R" in some words?

Question

What is the point for adding the "h" after the "r" in some words? Is it important for pronunciation or for spelling or for what? An example the word "Rhapsody" [Rapsode] or "Rhetoric" [retorek].

Answer 1

Initial 'rho' - the Greek letter 'r' - was accompanied by 'rough breathing' in Ancient Greek and in fact used to be written with a dot (a Daseia) over it when thus pronounced. Although later pronounced like and Italian or Spanish 'r', the 'rh' spelling was maintained when transliterated into Latin letters in order to reflect the earlier pronunciation.

An analogy in English would be the way we still write 'knight' even though the /k/ hasn't been sounded for years; or 'eight' from Old English 'eahta' where the /h/ was a bit like German or Scottish 'ch'. There are advantages for historical linguistics in preserving these older spellings although it makes it difficult for newcomers to learn to spell correctly.

Answer 2

I believe these words have Latin and Greek origins. There is no functional reason why we still spell them with the silent "h" but because they are borrowed words, the spellings have likely been standardized based on the original words.

Wish I had access to an OED. It could give you a more complete answer. For most modern words, a history of the word can be constructed, but it's impossible to say for sure who decided to put that pesky H in there.

Answer 3

Those words beginning with 'rho' stemming from Greek use to be written that way.
English use to keep the original form in most words