|Definition - A word or phrase that modifies something that is not clearly present or identified in the sentence.|
Example - Coming home last night, the house was dark.
(We dangle because we don't know who or what was coming home.)
Oxford English Dictionary - The term's first citation is from 1961:
"Let us examine, then, these dangling modifiers in ‘Bartleby’, looking at each of them in turn to see what … aid it can give us in understanding the obscurities of the tale."
(Amer. Speech XXXVI. 196)