What does beware mean?
Beware is a verb meaning to be cautious and on one's guard against danger, harm, or trouble. It is unusual among English verbs in that it survives almost entirely in the imperative mood: we say 'Beware of the dog' or 'You must beware,' but not 'she bewared.' It normally takes the preposition 'of' followed by whatever poses the threat, or a clause beginning with 'lest.' The word derives from the older phrase 'be ware,' combining 'be' with 'ware,' an old adjective meaning watchful or cautious that also gives us 'aware' and 'wary.' Because it is inherently a warning, beware carries an urgent, admonitory tone and appears constantly on signs, safety notices, and proverbial sayings such as 'let the buyer beware.' Its fixed, formulaic character makes it one of English's most recognizable cautionary words.
verbTo be cautious and on one's guard against danger or harm; used chiefly in the imperative as 'beware of' or 'beware lest', warning someone to take care.
- To be on guard against danger or harm, used chiefly in the imperative ('beware of', 'beware lest') as a warning.
"Beware of the dog."
"Travelers should beware of unofficial taxis operating outside the terminal."
"Beware lest you repeat the mistakes of the past."
'Caveat emptor' — buyer beware — is one of history's oldest consumer warnings, but English already had its own version: beware has been putting people on guard since the Middle Ages.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of beware
Beware arose in Middle English from the phrase 'be ware,' where 'ware' was an adjective meaning cautious or watchful. That adjective descends from Old English 'wær,' meaning attentive or vigilant, from a Germanic root also underlying 'wary' and giving us the prefixed forms 'aware' and 'unawares.' Over time the two-word phrase fused into the single verb beware, which by early modern English had settled into its modern, largely imperative usage. Its Germanic cousins include the related sense preserved in words like 'warehouse' only through spelling coincidence — 'ware' there is a different word meaning goods — so beware's true kin are the vigilance words: ware, aware, wary, and unawares.
How beware is actually used
Beware occurs almost exclusively in the imperative and infinitive-like constructions ('you must beware'); it does not take ordinary inflections like *'bewared'* or *'bewaring'*. It typically takes the preposition 'of', or a clause introduced by 'lest'. It carries an urgent, cautionary register and appears frequently in signage and warnings.
Easily confused with beware
'Aware' means simply having knowledge or notice of something, while 'beware' is a warning to be on guard against something dangerous.