Poets laureate vs. poet laureates
From Language Log: Why you can have poets laureate but not Nobels laureate:
In poet laureate (the title of whichever poet is currently designated as a kind of honorary official poet of the country), the head noun seems to be poet. So the plural is poets laureate, and that's what most people write.AP's related entry on the topic:
But in Nobel laureate, for some reason, things have shifted. Laureate is the head. It has become a noun. Nobel is an attributive modifier of it, as in Nobel prize. Hence the plural of Nobel laureate is Nobel laureates, a phrase which gets over four million Google hits. And Nobels laureate, as a plural NP, gets none. ...
On poet laureate, by the way, usage is split: poets laureate is the commonest plural, with 66,800 hits, but poet laureates gets a healthy 44,400. That means about 40% of speakers have reanalyzed laureate as a noun in that phrase too. This may well be an adjective that is dying out.
For those that involve separate words or words linked by a hyphen, make the most significant word plural:It's easy to see why poet laureate is difficult: A poet laureate is a poet and a laureate. (Follow the first plural listed in your dictionary, which is probably poets laureate.) A Nobel laureate, on the other hand, is a laureate but is not a Nobel.
--Significant word first: adjutants general, aides-de-camp, attorneys general, courts-martial, daughters-in-law, passers-by, postmasters general, presidents-elect, secretaries general, sergeants major.
--Significant word in the middle: assistant attorneys general, deputy chiefs of staff.
--Significant word last: assistant attorneys, assistant corporation counsels, deputy sheriffs, lieutenant colonels, major generals.
A Google News search turns up four poet laureates, three poets laureate (two in proper names and the other in England), 390 Nobel laureates and zero Nobels laureate.