[Pyramid*]

this is doing my head in and I cannot think of the term for it.

A sentence that has at least 3 consecutive words starting with the same letter...... there is a name for that but despite googling - I can't find it.

ie: The weather on that dark, dismal day deflated everyone

Any of the brainy students with a liking of English able to tell me what it is please? It's doing my nut in.