Add ‘s' to main element of compound:
A university professor commenting on a national television show about the election of several new governors used the term "governor-elects."
He should have said "governors-elect."
The rule is that the plurals of hyphenated or spaced compounds are formed by adding "s" to the main element of the compound.
In "governor-elect" the main word is "governor," and it gets the "s."
Other examples: "attorneys general," "fathers-in-law," "holes-in-one" and "runners-up."
But with nouns ending in "ful," the "s" is added at the end.
Examples: "cupfuls," "spoonfuls" and "mouthfuls."
