nisus

(Latin: from niti, to strive, to endeavor; effort, endeavor)

nisus
1. A striving, exertion, effort; an attempt or effort to accomplish an aim or goal.
2. Any strong effort or struggle.
nisus formativus
The periodic desire for procreation manifested in the spring season by certain species of animals.
oikonisus
The desire to start a family.