I very much wanted to believe that off of, rather than being a "stupid" usage, was in fact the correct formal usage of "off" in certain contexts, such as the one mentioned by FlameBoy above ("It fell off of a passing car"). My suspicions seemed to be confirmed by a visit to the Webster 1913 definition for off, which give many adjectival senses of "off" but only one sense in which off is a preposition:
Not on; away from; as, to be off one's legs or off the bed; two miles off the shore.
This sense is not the same as that described by FlameBoy, as it indicates position
rather than motion
. It would certainly sound wrong to say "the boat lay two miles off of the shore", but I reckoned that "the man fell off of the boat" actually sounds correct. My rationale
was that "off" could only be used as a preposition in one specific sense, in describing the position of the subject
. In every other sense "off" was an adjective
, and thus has to be used in conjunction
with the preposition "of
" to describe motion.
However, I have long ago learned not to trust Webster, even when it seems to confirm my own prejudices, so I wandered off to dictionary.com to get a second opinion. This site provided me with the following snippet from the American Heritage Dictionary (Fourth Edition, 2000):
Usage Note: The compound preposition off of is generally regarded as informal and is best avoided in formal speech and writing: He stepped off (not off of) the platform.
So it would appear that my initial apprehension was incorrect, and "off of" is indeed an informal and unnecessary way of saying "off".
However, I should point out that both of the sources I consulted are American, and I may have to revise this when I get a chance to consult a European source. It is possible that the usage rules described in the American Heritage Dictionary only apply to American usage, although I suspect this is not the case.