ciel, cieux, _heaven_, _heavens_.
{ _tester of a bed_; { _testers of beds_.
ciel { ciels {
{ _sky of a picture_; { _skies of pictures_.
oeil, yeux, _eye_, _eyes_.
oeil-de-boeuf, oeils-de-boeuf, _oval window_, _oval windows_.
aïeul, aïeuls, _ancestor_, _ancestors_.
aïeul, aïeuls, _grandfather_, _grandfathers_.
§ 6. PLURAL OF COMPOUND NOUNS.