Definition of erratic in English:



  • Not even or regular in pattern or movement; unpredictable.

    ‘her breathing was erratic’
    • ‘My sleep patterns have been so erratic this week that I've felt physically sick at times.’
    • ‘Steady breezes create regular rollers, while erratic squalls thrust up chaotic surges.’
    • ‘About 50 minutes later, just as people outside realized there was a problem, the elevator stopped its erratic movements.’
    • ‘Other grandparents fear the regular and erratic comings and goings and demands of the unfit parents of their grandchildren.’
    • ‘I did not know then that he had an erratic sleep pattern.’
    • ‘As the herd gained momentum the bells on the lead cows rang out louder and the erratic clanging became a regular tolling.’
    • ‘The Alice Springs district is dry for much of the year, and has an erratic rainfall pattern, with a slight summer maximum.’
    • ‘Of course, if that kind of erratic weather pattern appeared during winter, then I guessed that a blizzard would appear.’
    • ‘Just take for instance, the erratic rain pattern that hit parts of the country in the last farming season.’
    • ‘Global warming is also implicated in increasingly erratic arctic weather patterns.’
    • ‘Her blood pressure resumed its former erratic pattern.’
    • ‘The vehicle he was driving was stopped because of an erratic driving pattern typical of someone under the influence.’
    • ‘I think I prefer to see him as one of those ageing mongrels one sees with creaky back legs, white whiskers and erratic bowel movements.’
    • ‘I tried for a few photographs to show my appreciation but there was a frisky breeze, too light to notice if it were not for the constant erratic movement of flowers and leaves.’
    • ‘A wave of hands suddenly rose high in the air as each one moved about in erratic and unpredictable movements, each as unique as the children's personality.’
    • ‘Rapid eye movement sleep is characterized by a highly erratic breathing pattern and could not be simulated with current technology.’
    • ‘He still has this erratic speech pattern, the fluttering of the eyes, and he's the most appalling speechmaker.’
    • ‘The season of mists and mellow fruitfulness is upon us, but the erratic weather pattern has ensured there is still a lot of corn to cut and straw to gather.’
    • ‘Now scientists say the warming trend, if it continues, will increase the erratic weather patterns.’
    • ‘Room's movements were becoming more erratic and convulsive, and he seemed to have entered a trance-like state.’
    unpredictable, inconsistent, changeable, variable, inconstant, uncertain, irregular, unstable, turbulent, unsteady, unsettled, unreliable, undependable, changing, ever-changing, volatile, varying, shifting, fluctuating, fluid, mutable, protean, fitful, wavering, full of ups and downs
    mercurial, capricious, whimsical, fickle, flighty, giddy, impulsive, wayward, temperamental, highly strung, excitable, moody
    blowing hot and cold
    fluctuant, changeful
    View synonyms


  • A rock or boulder that differs from the surrounding rock and is believed to have been brought from a distance by glacial action.

    ‘the source of stone for the whetstones may have been glacial erratics’
    • ‘The rocks weighed about 40 kg and included two large pieces of unaltered vesicular basalt with many small attached organisms and numerous smaller rocks including a few glacial erratics.’
    • ‘Huge glacial erratics, boulders unlike most of the other rocks in their surroundings, stand in mute testimony to their cross-country transport by advancing ice.’
    • ‘The road itself twisted and contorted as much as the river as it dodged through and around clusters of trees and boulders: indigenous and erratics.’
    • ‘I stayed off the glacier, stumbling down the left moraine, often catching myself with my arms just before slamming into glacial erratics.’
    • ‘In the absence of other sources of building stone, glacial erratics have been extensively used in Finland and northern Poland.’


Late Middle English: from Old French erratique, from Latin erraticus, from errare to stray, err.