uncertain

adj

1. Not certain; unsure.

   “Conſider man without the protection and conduct of a ſuperior Being, and he is ſecure of nothing that he enjoys in this world, and uncertain of every thing that he hopes for.”

2. Not known for certain; questionable.

   “Tomorrow's weather is uncertain.”

3. Not yet determined; undecided.
4. Variable and subject to change.
5. Fitful or unsteady.

   “Turning back, then, toward the basement staircase, she began to grope her way through blinding darkness, but had taken only a few uncertain steps when, of a sudden, she stopped short and for a little stood like a stricken thing, quite motionless save that she quaked to her very marrow in the grasp of a great and enervating fear.”

6. Unpredictable or capricious.

   “O, woman! in our hours of ease, / Uncertain, coy, and hard to please, / And variable as the shade / By the light quivering aspen made; […]”

noun

1. (plural, plural-only, with-definite-article)Something uncertain.

   “Thinking about the uncertain refines our perception of the certain, and generally this takes place in a framework in which the uncertain is the future and the certain is the present.”