nisus

noun3

1. •
   A mental or physical effort to attain a specific goal; a striving.

   • The godly personality of a higher order, as the telos of the nisus of moral categoriality, is the sensus plenior of the nisus to a universal communalization of perspectives. — 1992
2. •
   The contraction of the diaphragm and abdominal muscles to evacuate faeces or urine.
3. •
   The periodic procreative desire manifested in the spring by birds, etc.