Prosthesis is adding an additional syllable to the beginning of a word. This can be done for several reasons. Sometimes, writers use prosthesis to emphasize the word. Sometimes, poets will use prosthesis so that the words adhere to the rhythm and meter of the poetry.
Examples of Prosthesis in Literature
From King Lear:
"Old fond eyes, be weep this cause again."
From Edgar Allan Poe's "A Dream Within a Dream":
Thus much let me avow-
You are not wrong, who deem
That my days have been a dream;
Yet if hope has flown away
Literary Terms Examples