Synonyms of the word

unpredictable

• adj. Unable to be predicted.
• n. An unpredictable thing.

aleatory

• adj. Depending on the throw of a die; random, arising by chance.

capricious

• adj. Impulsive and unpredictable; determined by chance, impulse, or whim.

episodic

• adj. relating to an episode.
• adj. sporadic, happening infrequently and irregularly.
• adj. (literature) made up a sequence of seemingly unconnected episodes.

freakish

• adj. Resembling a freak.
• adj. Strange, unusual, abnormal or bizarre.
• adj. Capricious, unpredictable.

indeterminable

• adj. That is incapable of being measured.
• adj. That is incapable of being ascertained.
• n. An indeterminable thing or quantity.

irregular

• adj. Nonstandard; not conforming to rules or expectations.
• adj. Of a surface, rough.
• adj. Without symmetry, regularity, or uniformity.
• adj. (geometry, of a polygon) Not regular; having sides that are not equal or angles that are not equal.
• adj. (geometry, of a polyhedron) Whose faces are not all regular polygons (or are not equally inclined to each…
• n. A soldier who is not a member of an official military force and, often, does not follow regular army tactics.
• n. One who does not regularly attend a venue.

occasional

• adj. Occurring or appearing irregularly from time to time.
• adj. Not very often.
• adj. Created for a specific occasion.
• adj. Intended for use as the occasion requires.
• adj. Acting in the indicated role from time to time.

sporadic

• adj. (archaic) (of diseases) occurring in isolated instances; not epidemic.
• adj. Rare and scattered in occurrence.
• adj. Exhibiting random behavior; patternless.

uncertain

• adj. Not certain; unsure.
• adj. Not known for certain; questionable.
• adj. Not yet determined; undecided.
• adj. Variable and subject to change.
• adj. Fitful or unsteady.
• adj. Unpredictable or capricious.
• n. (with "the") Something uncertain.

undeterminable

• adj. not possible to determine.

unforeseeable

• adj. Incapable of being foreseen or anticipated.