| Singular | Plural | |
|---|---|---|
| Nominativ | sincerus, sincera, sincerum, sincerumque | sincerae, sinceri, sincera |
| Genitiv | sinceri, sinceri, sincerae | — |
| Dativ | sincero, sincero, sincerae | sinceris |
| Akkusativ | sincerumque, sincerumque, sinceram, sincerum, sincerum | sinceras, sincera |
| Ablativ | sincero, sincero, sincera | sinceris |
| Vokativ | sincere, sincera, sincerum, sincerumque | sincerae, sinceri, sincera |
| Singular | Plural | |
|---|---|---|
| Nominativ | sincerius, sincerior | — |
| Genitiv | — | — |
| Dativ | — | — |
| Akkusativ | sincerius, sinceriorem | — |
| Ablativ | sinceriore | — |
| Vokativ | sincerius, sincerior | — |
| Singular | Plural | |
|---|---|---|
| Nominativ | sincerissimum | — |
| Genitiv | — | — |
| Dativ | — | — |
| Akkusativ | sincerissimum, sincerissimum | — |
| Ablativ | — | — |
| Vokativ | sincerissimum | — |