without warning; without notice
Used to describe an action or event that occurs suddenly, without prior notification or alert. Often appears in formal or written contexts.
The power went out without warning.
Dismissal without notice can be illegal in some cases.
Compound of 無 (mu, 'without') and 警告 (keikoku, 'warning'). The exact historical derivation is uncertain, but the word follows a common Sino-Japanese pattern for negation.