The Collaborative International Dictionary
Greengill
Greengill \Green"gill`\, n. (Zo["o]l.) An oyster which has the gills tinged with a green pigment, said to be due to an abnormal condition of the blood.
Wiktionary
greengill
n. An oyster which has the gills tinged with a green pigment, said to be due to an abnormal condition of the blood.