Why does eye become eyed in 'the blue-eyed boy'? Also, 'the three-legged dog', are there any rules to creating these forms?
I believe the logic behind it is this: in English you can verb nouns (which I've just done with the noun "verb"). So, a missing mental link between "blue eyes" and "blue-eyed" would be a verb "to blue-eye" which would mean "to give blue eyes to" ("blue-eyed" would be a regular past participle then).
It would be great to learn the history of the construction.
If you have a question about the English language and would like to ask one of our many English teachers and language experts, please click the button below to let us know: