In my opinion there's two defintions of "big": 1.) the subjective, personal opinion of a particular individual (otherwise known as bullshit), or, 2.) the factual, empirically proven results of an unbiased study
The best response here is from Stevenvegas from the first page, as he's quoting a small (300 men) but accurate study.
The first definition of big; an individuals personal definition, is usually so skewed from reality that its depressing. Example: me and a good friend of mine were hanging out with a group of mutual friends last weekend. One was a girl/woman of about 30 years old. She's reasonably attractive, and I've known her for a while and know for a fact that shes been with a good amount of different men (guessing at least 20 - 30). My buddy asked her "what's average" she said "i dunno, like 7 inches". Then he asked her whats big. She said "over 10 inches". If you haven't noticed whats wrong with this picture you may as well stop reading...I don't chalk this up to women being bad at measuring things, or that shes actually been with bigger (alot bigger)than average guys. Its more simple than that: as Jordan85 suggested; every guy who is about average says he is 7" 'cause its a respectable size according to popular opinion. So to her, all of the average guys shes been with were 7" or so. Then, to determine "big" its a simple tendency to add 2 or 3 inches to this figure as its not much extra when measuring any other object, but enough to be noticably larger. She may have even been with an 7.5 or 8" guy who said he was 10 or 12 or some other ridiculous number.
The second definition of big, a.k.a reality says this:
Length:
Tiny/micropenis...............< 3.8"
Small.............................3.8" to 4.6"
Below average.................4.6" to 5.5"
Average.........................5.5" to 6.3" (true average = 5.9")
Above average................6.3" to 7.1"
Big................................7.1" to 8"
Huge.............................> 8"
Consider this:
95% of all men are between 4.3" and 7.5"
50% of all men are between 5.5" and 6.3"
67% of all men are smaller than 6.3"
84% of all men are smaller than 6.7"
92% of all men are smaller than 7.1"
99% of all men are smaller than 8"
1 in 1,000 men are greater than 8.3"
Girth:
Tiny..........................< 3.65"
Small.........................3.65" to 4.15"
Just below average......4.15" to 4.65"
Average.....................4.65" to 5.15" (actual average = 4.9")
Just above average......5.15" to 5.65"
Big............................5.65" to 6.15"
Huge.........................> 6.15"
