alert

Word family

• alertness
  nounC1
• alerted
  adjectiveC1

Synonym discussion

Sense: verb/1

All four verbs cover the act of telling someone about something they need to know, but they differ in urgency, register, and content. 'Alert' carries the sharpest sense of immediacy: you alert the police, a hospital, or the public when action is needed now. 'Warn' is the broadest and most everyday; you can warn a child not to touch a hot pan, or warn a friend about a future risk that may never happen. 'Notify' is the most formal and neutral, common in offices, schools, and official letters — you notify HR of a change of address, with no danger implied. 'Caution' adds a tone of careful advice, often used by figures of authority: a judge cautions a witness, a coach cautions players against overconfidence. Compare: 'Witnesses alerted the police' (urgent), 'I warned my brother about the slippery floor' (everyday), 'Please notify the office by Friday' (administrative), 'The doctor cautioned her against heavy lifting' (advisory).

Common collocations

Etymology

'Alert' came into English in the late 1500s from the Italian military phrase 'all'erta', which literally means 'on the watch' or 'on the lookout' — 'erta' being a high lookout point or watchtower. French borrowed it as 'alerte', and English picked it up from there. It was first used as an adverb meaning 'on the watch', then quickly became an adjective for someone watchful and ready. The noun (a warning signal) and the verb (to warn) developed later, in the 1800s, as the word spread from military life into everyday English.