Instrumental should be formed to indicate tool/method of an action. It is similar to English "with":
He solves the equation with a computer.
He achieved it with his engagement.
He is trading with flowers.
Suffixes are different for gender and number.
Example for words: kameń (stone M), nož (knife M),
ruka
(hand F), voda (water F), auto (car N)
drevo (tree N):
| Nominative | Gender | Instrumental |
| +y muž nož | M | +ym mužom nožom |
| +a ruka voda |
F | +ou rukou vodou |
| +e drevo auto |
N | +ym drevom autom |
On trenuje velikym kameńom. (He is training with large stone.) M
Ona vodi go pravou rukou. (She leads him with right hand.) F
My sme jehali bystrym autom. (We rode with a fast car.) N
On myje se hladnou vodou. (He washes himself with cool water.) F
On trenuje težkymi kameńami. (He is training with heavy stones.)
Jastreb krmi se bielymi zajecami. (Hawk feed himself with white hares.)
Lepše je to objasniť pravdivymi prikladami.
(It's better to explain it with true examples.)
Example for irregular plural words: oči (eyes), sotni (hundreds):
Sviedek videl to vlastnymi očiami. (The witness saw it with own eyes.)Nastupna strana: Latinisms