erratical
/ɪˈrætɪkəl/
adjective
- Not following a regular or predictable pattern; tending to change suddenly and without reason.
- The stock market has been erratical this month, rising and falling without warning.
- The old car's erratical engine made it hard to drive on the highway.
- Her erratical mood swings confused everyone in the office.
Antonyms