The word “fulsome” presents a problem that usage and etymology fail to sort out. It either means “abundant,” “offensive” or, perhaps as a compromise, “offensively abundant.” Dictionaries usually give at least the first two meanings while most usage guides insist on the third. The Associated Press Stylebook says “it means disgustingly excessive” and should not be used to mean “lavish or profuse.” The BBC News Styleguide says, probably incorrectly, that “fulsome is not a close relative of full, and does not mean generous.”
The word might have derived from the word “foul,” giving the “offensive” meaning credence. But the Oxford English Dictionary and others suggest it comes from “full.” The OED’s corpus has a century of examples where the word meant “abundance” before examples where “excessive” or “foul” came into play.
The negative sense seems to have surpassed the positive sense centuries ago, although in recent usage the positive sense seems to predominate. According to the Online Etymology Dictionary, “since the 1960s, however, it commonly has been used in its original, favorable sense, especially in ‘fulsome praise.’”
In its 2002 survey of its usage panel, the American Heritage Dictionary found only 16 percent support for the “abundant” sense in the example: “The final report will furnish a more detailed and fulsome discussion of the details involved.”
How, then, should it be used? In the interest of clarity, it probably shouldn’t. Paul Brians on his “Common Errors in English Usage” website says of the disagreement over the word: “The first group tends to look down on the second group, and the second group tends to be baffled by the first. Best to just avoid the word altogether.”
If you use “fulsome” to mean “abundant,” you are likely to be corrected by those inclined to correct you. And it might be read as a negative anyway. Australia’s minister for climate change recently called a meeting with big polluters “constructive and fulsome” (Sydney Morning Herald, April 8, 2011). The context makes the meaning clear, but one has to wonder if he wasn’t making a joke with the double meaning.
You are probably safest to use it in the sense of negatively abundant if the context is clear: “…the crude or even vulgar products of our fulsome commodity society.” (Hoeveler, “Watch on the Right,” 1991). Clarity is achieved, and no nasty notes would question your use of the language.
But if those nasty notes from language peeves don’t bother you when history and common usage are on your side, go ahead and use “fulsome” to mean abundant. Just be careful your meaning is clear.