Being in a dilapidated condition, I was able to buy the house very cheap.

— from the 1918 edition of The Elements of Style

In grammar a dangling modifier or misplaced modifier is a word or clause that modifies another word or clause ambiguously, possibly causing confusion with regard to the speaker's intended meaning.

A dangling modifier is problematic because it can potentially apply to either the subject or the object of the sentence it is attached to. For example the sentence "Being ill in bed, the telephonist startled me when she rang" has two possible interpretations: it could either mean the telephonist (the subject), or the speaker ("me", the object) is ill in bed.

Often sentences with dangling modifiers are not ambiguous for pragmatic reasons, for example "Being ill in bed, the telephone startled me when it rang" is unambigous, for the obvious reason that telephones can't be ill. Even when unambiguous, however, dangling modifiers are still rejected by most style guides; most sentences with dangling modifiers can be easily and harmlessly rearranged to avoid any possibility of confusion: "Being ill in bed, I was startled by the telephone ringing".

Adverbial phrases or adverbs are often used in a similar way to dangling modifiers.

One of the greatest stylistic controversies of the last thirty or so years has been that of the dangling adverb "hopefully". Observers began to object when they first encountered constructions such as "hopefully, the sun will be shining tomorrow", arguing that it is not the sun but the speaker who hopes that the sun will shine. This argument is largely based on a misunderstanding of the grammatical structure of the sentence: "hopefully", when used in this fashion, is modifying the whole sentence, not the subject of the sentence, and is similar to many other adverbs in this respect (e.g. "admittedly", "mercifully", "oddly"). Generally this use of the adverb does not create ambiguity, for example most speakers can interpret "Hopefully John was home last night" only as meaning that the speaker hopes that John was home last night, not that John was home last night in a hopeful manner. In recent years this usage has become much more acceptable to many, perhaps because its semantics are reminiscent of the German hoffentlich ("it is to be hoped that") which does, in fact, mean that it is the speaker who "hopes that the sun will shine".

See garden path sentence for another stylistic pitfall that is related to the dangling modifier in the way it causes confusion.