Q: I have a question about the use of “so” in constructions like “I so appreciate your website” or “I so want to help.” Is this correct usage? It sounds awkward to my ears, and I would substitute the word “really” for “so” here.
A: Used with a verb, “so” can be an intensifier, as it is in the two sentences you mention. This usage is standard English, and the Oxford English Dictionary has citations for it dating back to 1375.
It can precede the verb, as in this line by the poet Edmund Spenser (1579): “What payne doth thee so appall?” Or it can follow, as in this quotation from a story by Charles Gibbon (1884): “I held back because I loved you so.”
The use of the adverb “so” in sentences like these can also be read as elliptical (that is, as a short form) for “so much.”
Using your examples and assuming “so” is being used ellipitically, the complete versions would read: “I so much appreciate your website” … and … “I so much want to help.”
These can be reversed: “I appreciate your website so much” … and … “I want so much to help.”
Here, “so much” is an adverbial phrase (similar to “very much”) that modifies the verbs “appreciate” and “want.”
There’s also a slangy use of “so” in which the word is used as an intensifier to form what the OED calls “non-standard grammatical constructions.” Example: “You’re so Brooks Brothers.”
Here, “so” is used in unexpected ways to modify a noun or noun phrase, a verb, an adjective, or another adverb. Its meaning is “extremely” or “decidedly.”
The earliest citation in Oxford is dated 1923, from Ronald Firbank’s novel The Flower Beneath the Foot: “What can you see in her…? She’s so housemaid.”
But this appears to be an isolated example, the OED says, and unrelated to the avalanche of late 20th-century usages. Here’s a sampling of those:
“You’re so the opposite!” – 1979, from the movie Annie Hall, written by Woody Allen and Marshall Brickman.
“Grow up, Heather. Bulimia’s so ’86.” – 1988, from the movie Heathers, written by Daniel Waters.
“We so don’t have time.” – 1996, from a Buffy the Vampire Slayer episode, written by Joss Whedon.
“The kid gloves are so off.” – 2001, in the magazine Heat.
“I am so getting the milkshake.” – 2004, in the New York Times.
“You’ve seen the carousel and it’s so not cool to be seen here if you’re over nine years old.” – 2005, from Jan M. Czech’s novel Grace Happens.