| Case | Singular | Plural |
|---|---|---|
| nom | lapsus | lapsy, lapsusy |
| gen | lapsu, lapsusu |
lapsů, lapsusů |
| dat | lapsu, lapsusu |
lapsům, lapsusům |
| acc | lapsus | lapsy, lapsusy |
| voc | lapse, lapsuse |
lapsy, lapsusy |
| loc | lapsu, lapsusu |
lapsech, lapsusech |
| instr | lapsem, lapsusem |
lapsy, lapsusy |