erratic
1. [ adjective ] liable to sudden unpredictable change
Synonyms: mercurial quicksilver fickle
Examples:

"erratic behavior" "fickle weather" "mercurial twists of temperament" "a quicksilver character, cool and willful at one moment, utterly fragile the next"

Related terms: changeable
2. [ adjective ] having no fixed course
Synonyms: wandering planetary
Examples:

"an erratic comet" "his life followed a wandering course" "a planetary vagabond"

Related terms: unsettled
3. [ adjective ] likely to perform unpredictably
Synonyms: temperamental
Examples:

"erratic winds are the bane of a sailor" "a temperamental motor sometimes it would start and sometimes it wouldn't" "that beautiful but temperamental instrument the flute"- Osbert Lancaster

Related terms: unreliable
Similar spelling:   erotic
  erotica
  eroticism
  eradicate
  erotically
  eradicator
  eradicable
  erotism