The Manx shearwater belongs to the Procellariidae family - a family of tubenose seabirds which includes (as far as us Brits are concerned) the fulmar and the shearwaters.
The Manx shearwater is strange in that its scientific name of Puffinus puffinus records a name shift or a change in nomenclature if you will - and also is an example of a scientific name not rooted in a classical language such as Latin or Greek.
Before the 18th century, Manx shearwaters were called "Manks puffins" - the word "puffin" being derived from "pophyn" a middle English word which meant "Fatling" - a cured baby shearwater carcass (eaten as food).
We can only guess that the bird we now call the "puffin" (in common parlance) took its name purely because it is a pelagic seabird like the original pophyns (shearwaters) and exhibits similar nesting habits - i.e. nests in subterranean burrows on the same cliff-tops often - and that's about that really - the fatlings (young of the shearwater) and puffins were simply confused.
We'll come onto the (Atlantic) puffin's (more amusing) scientific name in a later blog.
Anyway... the literal translation of the Manx shearwater's scientific name can be thought of as:
"cured, plump, baby seabird carcass - cured, plump, baby seabird carcass".