Question: “Hi Jordan,
Can you comment on “off of?” [As in] “I jumped off of the rock.” This is another favorite phrase.” (From Caroline Rosewell)
Answer: Caroline: Happy to comment, and I appreciate the jumping off point.
The “off of” construction is at best anachronistic, and at worst redundant. We’ll look at why below.
To begin, both “off” and “of” are prepositions. Their meanings overlap when they are used to indicate the object of an action – as they are in the example sentence, “I jumped off of the rock.” They do not function equally in that role, however.
Consider them individually: “I jumped off the rock.” “I jumped of the rock.” The former makes sense – the latter does not.
You could argue, I suppose, that “off” functions as an adverb modifying the prepositional phrase “of the rock” – which is itself functioning as an adverbial phrase modifying “jumped” – but that seems to me to be the grammatical equivalent of taking a plane to Chicago so that you can catch a bus to Denver. Just take the plane straight there.
What I think is actually happening here is that “off of” is being substituted where “from” should go, i.e. “I jumped from the rock.” The preposition “from” is used specifically to indicate the starting point of a physical movement, and is probably the best choice in this scenario, with “off” being an acceptable second option and “off of” not even qualifying.
In conclusion, when you feel an “off of” about to slip out of your mouth, just stop at “off.” Even better, consider using “from.” And if, for whatever reason, you find a better deal flying to Chicago and then taking a bus – by all means, go for it. Who am I to stand in the way of saving a buck?