Mint (M) Absolutely perfect in every way - certainly never played, possibly even still sealed. (More on still sealed below). Should be used sparingly as a grade, if at all.
Near Mint
(NM or M-)
A nearly perfect record. Many dealers won't give a grade higher than this implying (perhaps correctly) that no record is ever truly perfect. The record shows no obvious sign of   wear. A 45 rpm sleeve has no more than the most minor defects, such as almost invisible ring wear or other signs of slight handling. An LP jacket  has no creases, folds, seam splits or any other noticeable similar defect. No cut-out holes, either. And of course, the same is true of any other inserts, such as posters, lyric sleeves, and the like. Basically, Near Mint looks as if you just got it home from a new record store and removed the shrink wrap.
Very Good Plus
(VG+)
Shows some signs that it was played and otherwise handled by a previous owner who took good care of it. Record surfaces may show some slight signs of wear and may have slight scuffs or very light scratches that don't affect one's listening experience. Slight warps that do not affect the sign are OK. The label may have some ring wear or discoloration, but is should be barely noticeable. The center hole is not misshapen by repeated play.  Picture sleeves and LP inner sleeves will have some slight wear, lightly turn-up corners, or a slight seam-split. An LP jacket my have slight signs of wear also and may be marred by a cut-out hole, indentation or corner indicating it was taken out of print and sold at a discount. In general, if not for a couple of minor things wrong with it, this would be Near Mint. All but the most mint-crazy collectors will find a Very Good Plus record highly acceptable.
This grading guide is reprinted from Goldmine magazine, which is considered to be the standard for record collectors worldwide.   Very Good
(VG)
 
Many of the defects found in a VG+ record are more pronounced in a VG disc. Surface noise is evident upon playing, especially in soft passages and during the song's intro and fade, but will not overpower the music otherwise. Groove wear will start to be noticeable, as will light scratches (deep enough to feel with a fingernail) that will affect the sound. Labels may be marred by writing, or have tape or stickers (or their residue) attached. The same will be true of picture sleeves or LP covers. However, it will not have all of these problems at the same time, only two or three of them.
Good
(G),
Good Plus
(G+)
Good does not mean bad! A record in Good or Good Plus condition can be put onto a turntable and will play through without skipping. But it will have significant surface noise and scratches and visible groove wear. A jacket or sleeve has seem splits, especially at the bottom or on the spine. Tape, writing, ring wear or other defects will start to overwhelm the object. If it's a common item, you'll probably find another copy in better shape eventually. Pass it up. But if it's something you have been seeking for years, and the price is right, get it.
Poor
(P),
Fair
(F)
The record is cracked, badly warped, and won't play through without skipping or repeating. The picture sleeve is water damaged, split on all three seams and heavily marred by wear and/or writing. The LP jacket barely keeps the LP inside it. Inner sleeves are fully seam split, and written upon. Except for impossibly rare records otherwise unattainable, records in this condition should be bought or sold for no more than a few cents each
Still Sealed
(SS)
Let the buyer beware, unless it's a U.S. pressing from the last 10-15 years or so. It's too easy to reseal on. Yes, some legitimately never-opened LPs from the 1960s still exist. But if you're looking for a specific pressing, the only way you can know for sure is to open the record. Also, European imports are not factory-sealed, so if you see them advertised as sealed, someone other than the manufacturer sealed them.
Circle Sky Records Grading Addendum:      
    ++ or -- On occasion, in an attempt to better describe the condition of a record or cover, we will use an additional + or - sign. As an example, if a record was somewhere between VG+ and NM, in fairness we would describe it as VG++.
    Ring Wear We used the grading methods, as outlined above, but when ring wear was a major cause, of the grade, we try to make a notation so you will know what to expect. If we say "Some", "A Little" or "Minor" ring wear - then you should expect that you'll see a very tiny amount of wearing (sometimes very faint and hardly worth mentioning)...certainly not ruining the look of the cover. If we say "Medium" ring wear, you should expect noticeable wear that still does not completely ruin the look of the cover. If we just say "Ring Wear" or "Bad Ring Wear", etc. - you should expect that the ring wear will be very noticeable and pretty much overwhelming the look of the cover. Note: We will say "Front" or "Back" when only one side is affected.