A dangling modifier is a clause which says something other than the one intended because words are ordered incorrectly or left out. The meaning of the sentence, therefore, is left "dangling." A clause may have been intended to modify the subject, but word order makes the modifier seem to modify an object instead.

For example, Turning left on University Avenue, a large bookstore came into view. This should have been written: Turning left on University Avenue, I saw a large bookstore.