Unhinged - a stamp without hinge marks, but not necessarily with original gum.
Unitrade Specialized Catalogue of Canadian Stamps - specialized stamp catalogue published by Unitrade Associates on an annual basis.
Unhinged - A stamp without hinge marks.
Unissued - Stamp prepared for postal use but which are not issued.
- Unhinged, a regummed stamp that has not been affixed to a hinge or a stamp mount.
UHM stands for Unhinged Mint - the stamp is in the condition it was in when first purchased. M stands for Hinged Mint - the stamp has previously been mounted in a collection. U stands for Used - the stamp is postmarked but not heavily.
Since the time that unhinged stamps became popular, considerable numbers of old stamps with intact gum have appeared on the market, raising suspicion that many of these have been regummed.
 References ...
Hinging mint stamps causes them to lose some of the original gum, thereby causing them to be worth less than they would be if they were unhinged.
Stamp Mounts - These are considerably more expensive than hinges.
He hadn't thought of an unhinged sheet and typewriter. Another collector-of the true amateur type-had duplicates and triplicates of valuable stamps mounted one under the other in a printed album.
See also: Stamp, Used, Hinged, Hinge, Mint