Watchout

Part of speech: noun, interjection

Definitions

1. A careful lookout kept for possible danger, trouble, or an approaching threat
2. An alert or sentry posted to notice risks before they cause harm
3. The act of staying vigilant for hazards, or the person or post doing so

Etymology: "Watchout" is a deverbal formation, meaning it was created by turning the phrasal verb "watch out" into a noun (and it also works as an interjection). The phrase "watch out" itself is built from "watch" and the adverb "out," so the compound gathers its sense from the pairing: to keep alert and look for danger. Used as a noun, the word names a warning or a lookout, something to be wary of. As an interjection, it is simply a shouted alert, a shorter way of saying "be careful." Its pattern follows other English nouns that were made from phrasal verbs, such as "takeoff" or "breakdown," where a two-part verb is compressed into a single word that can stand as a thing or an exclamation.

Synonyms: warning, caution, alert, heads up