Greenwood, who toured with the Lions in 1997, 2001 and 2005, was the most-recent uncapped player to be named in a Lions party when he travelled to South Africa under Ian McGeechan 12 years ago.
The 36-year-old ex Harlequins and Leicester star knows that it is unlikely that anyone will repeat that feat this time around, although he admits that such an inclusion would certainly raise a few eyebrows.
"I think most people would be pretty convinced that 27 or 28 names are pretty much nailed on, and there are seven or eight names to fill," said Greenwood.
"Would you count, for example, Tomas O'Leary as a bolter? Possibly, at the start of the season most people outside of Munster may not have heard too much about him.
"Is Ben Foden a bolter? Is Thom Evans a bolter? I would be fascinated if there was an uncapped player.
"And what is the definition of the word bolter? Is it someone that no-one has spoken or talked about during the past six months? In which case, there isn't a rugby player in the northern hemisphere who has been hiding under the rock that long."
One surprise Greenwood believes Lions head coach Ian McGeechan may still throw into the pot, however, is the inclusion of Jonny Wilkinson.
Greenwood played alongside the Newcastle fly-half in England's World Cup winning side and knows better than most the attributes Wilkinson possesses.
Although Greenwood himself says he would not select his former team-mate due to a lack of game time since dislocating his knee at the end of September, he claims he would not be shocked if Wilkinson is on the plane to South Africa next month.
"Ronan O'Gara and Stephen Jones are the number one and two fly-halves on this tour, in my opinion," added Greenwood.
"They are going to take a third fly-half, you would have thought.
"Has Jonny got enough game-time underneath his belt? Would I be putting him in that squad on April 21? No I wouldn't, but if McGeechan puts him in the squad you certainly wouldn't get any arguments from me."