The word for today is…
alliteration (noun) – The repetition of identical or similar sounds at the beginning of words or in stressed syllables, as in “on scrolls of silver snowy sentences”. Modern alliteration is predominantly consonantal; certain literary traditions, such as Old English verse, also alliterate using vowel sounds.
Source : The Free Dictionary
Etymology : 1650s, “a beginning with the same letter,” from Modern Latin alliterationem (nominative alliteratio), noun of action from past participle stem of alliterare “to begin with the same letter,” from Latin ad- “to” + littera (also litera) “letter, script”.