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