Messier Objects

The Messier objects are a set of astronomical objects catalogued by the French astronomer Charles Messier in his "Catalogue des Nébuleuses et des Amas d'Étoiles" ("Catalogue of Nebulae and Star Clusters"), originally published in 1771, with the last addition (based on Messier's observations) made in 1966.

Because Messier was interested in finding only comets, he created a list of non-comet objects that frustrated his hunt for them. The compilation of this list, in collaboration with his assistant Pierre Méchain, is known as the Messier catalogue. This catalogue of objects is one of the most famous lists of astronomical objects, and many Messier objects are still referenced by their Messier number.

The first edition included 45 objects, with Messier's final list totaling 103 objects. However, Messier 102 was not reported correctly, bringing the total to 102 objects. Other astronomers, using side notes in Messier's texts, eventually filled out the list to 110 objects.

Reference
Wikipedia

Term first found in HGS Manual: Page 108