Mawson, C.O.S., ed. (1870–1938). Roget’s International Thesaurus. 1922.

Class IV. Words Relating to the Intellectual Faculties
Division (I) Formation of Ideas
Section III. Materials for Reasoning

475. Uncertainty.

   NOUN:UNCERTAINTY, incertitude, doubt; doubtfulness &c. adj.; dubiety, dubitation, dubitancy [obs.], dubiosity, dubiousness.
  HESITATION, suspense, state of suspense; perplexity, embarrassment, dilemma, Morton’s fork [hist.], bewilderment; botheration [colloq.]; puzzle, quandary; timidity (fear) [See Fear]; vacillation [See Irresolution]; aporia, diaporesis, indetermination; sealed orders.
  VAGUENESS &c. adj.; haze, fog; obscurity (darkness) [See Darkness]; ambiguity (double meaning) [See Equivocalness]; contingency, double contingency, possibility upon a possibility; open question (question) [See Inquiry]; onus probandi [L.], blind bargain, pig in a poke, leap in the dark, something or other; needle in a bottle of hay; roving commission.
  FALLIBILITY; unreliability, unreliableness, untrustworthiness; precariousness &c. adj.
   VERB:BE UNCERTAIN &c. adj.; wonder whether.
  lose the -clew or clue, – scent; miss one’s way, wander aimlessly, beat about, hang around.
  not know -what to make of (unintelligibility) [See Unintelligibility], – which way to turn, – whether one stands on one’s head or one’s heels; float in a sea of doubt, hesitate, flounder; lose oneself, lose one’s head; muddle one’s brains.
  RENDER UNCERTAIN &c. adj.; put out, pose, puzzle, perplex, embarrass; muddle, confuse, confound; bewilder, bother, moider [dial.], rattle [colloq.], nonplus, addle the wits, throw off the scent, keep in suspense, keep one guessing.
  DOUBT, (disbelieve) [See Unbelief. Doubt]; hang in the balance, tremble in the balance; depend.
   ADJECTIVE:UNCERTAIN, unsure; casual; random (aimless) [See Chance]; changeable, changeful [See Changeableness].
  DOUBTFUL, dubious; dazed; insecure, unstable, indecisive; unsettled, undecided, undetermined; in suspense, open to discussion; controvertible; in question (inquiry) [See Inquiry].
  VAGUE; indeterminate, indefinite; ambiguous, equivocal; undefined, undefinable, confused (indistinct) [See Invisibility]; mysterious, cryptic, veiled, obscure, oracular.
  PERPLEXING &c. v.; enigmatic, paradoxical, apocryphal, problematical, hypothetical; experimental [See Experiment].
  FALLIBLE, questionable, precarious, slippery, ticklish, debatable, disputable; unreliable, untrustworthy.
  UNAUTHENTIC, unauthenticated, unauthoritative; unascertained, unconfirmed; undemonstrated; untold, uncounted.
  CONTINGENT, contingent on, dependent on; subject to; dependent on circumstances; occasional; provisional.
  in a state of uncertainty, on the horns of a dilemma, in a cloud, in a maze; bushed, off the track; derailed; ignorant [See Ignorance]; afraid to say; out of one’s reckoning, out of one’s bearings, astray, adrift; at sea, at fault, at a loss, at one’s wit’s end, at a non-plus; puzzled &c. v.; lost, abroad, désorienté [F.]; distracted, distraught.
   ADVERB:UNCERTAINLY &c. adj.; at random, until things straighten out, while things are so uncertain, in this state of suspense; pendente lite [L.]; sub spe rati [L.].
  1. Heaven knows.
  2. Who can tell?
  3. Who shall decide when doctors disagree?
  4. Spargere voces in vulgum ambiguas.—Vergil
  5. He is no wise man who will quit a certainty for an uncertainty.—Johnson
  6. A little philosophy inclineth man’s mind to atheism, but depth in philosophy bringeth men’s minds about to religion.—Bacon
  7. Dum in dubio est animus paulo momento huc illuc impellitur.—Terence
  8. To-morrow is, ah, whose?—Mulock
  9. Unborn To-morrow and dead Yesterday.—Omar Khayyám—Fitzgerald
  10. Gather ye rose-buds while ye may.—Herrick
  11. Uncertainty! Fell demon of our fears! The human soul, That can support despair, supports not thee.—Mallet
  12. There is such a choice of difficulties, that I own myself at a loss how to determine.—General James Wolfe—Dispatch to Pitt