| Nominativ | placida, placidum, placidaque, placidus, placidusque, placidaeque | placidique, placida, placidaque, placidae, placidaeque, placidi |
| Genitiv | placidique, placidique, placidae, placidi, placidi | placidarum, placidorum, placidorum |
| Dativ | placido, placido, placidae, placidoque, placidoque | placidis |
| Akkusativ | placidam, placidamque, placidum, placidum | placidos, placida, placidaque, placidas, placidaeque |
| Ablativ | placida, placidaque, placido, placido, placidoque, placidaeque, placidoque | placidis |
| Vokativ | placida, placidum, placidaque, placide, placideque, placidaeque | placidique, placida, placidaque, placidae, placidaeque, placidi |
