Stamp Collecting Abbreviations

The world of stamp collecting can sometimes be a bit overwhelming for new stamp collectors, and the hobby is full of somewhat cryptic abbreviations, which can make things even more confusing to a beginner. Here are some of those abbreviations decoded.

NHM Never Hinged Mint
MNH Mint Never Hinged
UM, U/M or U.M. Unmounted Mint
UHM Unhinged Mint
Mint NH Mint Never hinged

The above abbreviations all mean the same thing, and stamps described that way should be POF - Post Office Fresh.

Then there is ...

MH Mint Hinged
MM Mounted Mint
LMM Lightly Mounted Mint
MLH Mint Lightly Hinged
LHM Lightly Hinged Mint
Unused Mint no Gum, Issued Without Gum
MHH Mint Heavy Hinge
MNG Mint No Gum
OG Original Gum (original gum is present and not re-gummed)
Part OG Partial Original Gum
Used Postally Used
CTO Canceled To Order

Are you confused yet? Some stamp dealers also use these abbreviations:

* Mounted Mint or Mint Hinged
** Unmounted Mint or Mint Never Hinged
o Used


Here's some of these abbreviations used in context.

If you buy a stamp at your post office (PO) the stamp will be UM, U/M, U.M., MNH, NHM, UHM or Mint NH. If you put a hinge on it it will no longer be any of those, and it will no longer be POF. It will instead be MH, MLH, LHM, MHH (if you are heavy handed with your hinges), MM or LMM.

If you hand the stamp to your postal clerk and ask for it to be canceled even though it's not on an envelope and will not be mailed, it will become CTO (sometimes also called a "favor cancel.")

If you use your stamp to mail something and it arrives in the mail without being canceled (i.e., the cancellation machine missed it) it will be classed as MNG or Unused. If it arrives canceled then it will be Used.