erratic
adj.moving or behaving in a way that is not regular or certain. You use this to describe something that changes suddenly and is hard to predict.
adj.characterised by lack of consistency, regularity, or uniformity. Often describes movement, behaviour, or data patterns that deviate from expected paths.
“The car's erratic movements made the other drivers nervous.”
“The stock market has shown erratic behavior lately, with prices jumping up and down for no clear reason.”
“Despite the athlete's undeniable talent, his erratic training schedule and unpredictable mood swings eventually led the coach to remove him from the starting lineup.”
Often used to describe physical motion, weather patterns, or human behavior; frequently follows linking verbs like 'become' or 'remain'.
“Erratic rainfall and hotter temperatures have also made access to water unpredictable despite several government and community-led conservation efforts.”
“The first weeks of a new season after a major tournament, especially the World Cup, are often a little erratic anyway, but this feels like a particularly unpredictable start to a campaign.”
From Middle English erratik, erratyk, from Latin errāticus; compare Old French erratique.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.