ˈnīsəs noun
( plural nisus )
Etymology: Latin, from nisus, past participle of niti to bear down, strive; akin to Latin conivēre, connivēre to close the eyes — more at connive
1. : a conative state or condition : striving , inclination
a nisus or energizing towards a presented object — L.P.Hickok
this nisus towards individuality — R.H.Gault & D.T.Howard
a nisus towards large generalizing — George Saintsbury
2. : a tendency or principle in reality according to some philosophers exhibited in the emergence of higher levels of existence (as life, mind, deity)
there is a nisus in space-time which, as it has borne its creatures forward through matter and life to mind, will bear them forward to some higher level of existence — Samuel Alexander