n. 1. an exceedingly short-lived meson. [ WordNet 1.5 ]

n. (Embryology) the area of the mesoderm that forms the notochord. [ WordNet 1.5 ]

a. [ Pref. circum- + esophagal. ] (Anat.) Surrounding the esophagus; -- in (Zool.) said of the nerve commissures and ganglia of arthropods and mollusks. [ 1913 Webster ]

a. (Anat.) Circumesophagal. [ 1913 Webster ]

n. [ Dorsum + meson. ] (Anat.) See Meson. [ 1913 Webster ]

a. Gay; sportive; playful; frolicsome; merry. Shak. [ 1913 Webster ]

Gladness of the gamesome crowd. Byron.

-- Game"some*ly, adv. -- Game"some*ness, n. [ 1913 Webster ]

n. A sparrow-sized fossil bird of the Lower Cretaceous having a strutlike pectoral bone and vestigial tail; found in Spain; considered possibly the third most primitive of all birds. [ WordNet 1.5 ]

prop. n. A genus of xerophytic ferns of South America.
Syn. -- genus Jamesonia. [ WordNet 1.5 ]

n. [ From Prof. Jameson, of Edinburgh. ] (Min.) A steel-gray mineral, of metallic luster, commonly fibrous massive. It is a sulphide of antimony and lead, with a little iron. [ 1913 Webster ]

{ . [ Gr. me`sos in the middle. ] 1. A combining form denoting in the middle, intermediate. [ 1913 Webster ]

2. specif. (Chem.), Denoting a type of hydrocarbons which are regarded as methenyl derivatives. Also used adjectively. [ 1913 Webster ]

3. (Chem.) Optically inactive due to compensating optical activity at two or more asymmetric centers, often due to a plane of symmetry within the molecular structure; as, meso-tartaric acid. [ PJC ]

4. Attached to a carbon atom located between two hereoatoms in a heterocyclic ring. [ PJC ]

‖n. [ NL., from Gr. me`sos middle + 'w, a`rion, dim. of 'w, o`n an egg. ] (Anat.) The fold of peritoneum which suspends the ovary from the dorsal wall of the body cavity; the mesovarium. [ 1913 Webster ]

n. [ Meso- + -blast. ] (Biol.) (a) The mesoderm. (b) The cell nucleus; mesoplast. [ 1913 Webster ]

a. (Biol.) Relating to the mesoblast; as, the mesoblastic layer. [ 1913 Webster ]

a. [ Meso- + branchial. ] (Zool.) Of or pertaining to a region of the carapace of a crab covering the middle branchial region. [ 1913 Webster ]

‖n.; pl. Mesobronchia [ NL. See Meso-, and Bronchia. ] (Anat.) The main bronchus of each lung. [ 1913 Webster ]

‖n. (Anat.) [ NL. See Meso-, and Caecum. ] The fold of peritoneum attached to the caecum. -- Mes`o*cae"cal a. [1913 Webster]

n. [ Meso- + Gr. karpo`s fruit. ] (Bot.) The middle layer of a pericarp which consists of three distinct or dissimilar layers. Gray. [ 1913 Webster ]

a. [ Meso- + cephalic. ] (Anat.) (a) Of or pertaining to, or in the region of, the middle of the head; as, the mesocephalic flexure. (b) Having the cranial cavity of medium capacity; neither megacephalic nor microcephalic. (c) Having the ratio of the length to the breadth of the cranium a medium one; mesaticephalic. [ 1913 Webster ]

‖n. [ NL. See Meso-, and Cephalon. ] (Anat.) The pons Varolii. [ 1913 Webster ]

a. (Anat.) Mesocephalic. [ 1913 Webster ]

{ ‖ } n. [ NL. mesocoelia. See Meso-, and Coelia. ] (Anat.) The cavity of the mesencephalon; the iter. [ 1913 Webster ]

n. [ NL., fr. Gr. meso`kwlon; me`sos middle + kw^lon the colon: cf. F. mésocôlon. ] (Anat.) The fold of peritoneum, or mesentery, attached to the colon. -- Mes`o*col"ic a. [1913 Webster]

n. [ Meso- + coracoid. ] (Anat.) A process from the middle of the coracoid in some animals. [ 1913 Webster ]

{ } n. [ Meso- + cuneiform, cuniform. ] (Anat.) One of the bones of the tarsus. See 2d Cuneiform. [ 1913 Webster ]

n. [ Meso- + Gr. de`rma skin. ] (Biol.) (a) The layer of the blastoderm, between the ectoderm and endoderm; mesoblast. See Illust. of Blastoderm and Ectoderm. (b) The middle body layer in some invertebrates. (c) The middle layer of tissue in some vegetable structures. [ 1913 Webster ]

a. (Biol.) Pertaining to, or derived from, the mesoderm; as, mesodermal tissues. [ 1913 Webster ]

a. Same as Mesodermal. [ 1913 Webster ]

a. [ Meso- + Gr. 'odoy`s, 'odo`ntos, a tooth. ] (Anat.) Having teeth of moderate size. [ 1913 Webster ]

‖n. [ NL., fr. Gr. me`sos middle + &unr_; belly. ] (Anat.) The fold of peritoneum connecting the stomach with the dorsal wall of the abdominal cavity; the mesogastrium. [ 1913 Webster ]

a. [ Meso- + gastric. ] [ 1913 Webster ]

1. (Anat.) (a) Of or pertaining to the middle region of the abdomen, or of the stomach. (b) Of or pertaining to the mesogaster. [ 1913 Webster ]

2. (Zool.) Of or pertaining to the middle gastric lobe of the carapace of a crab. [ 1913 Webster ]

‖n. [ NL. See Mesogaster. ] (Anat.) (a) The umbilical region. (b) The mesogaster. [ 1913 Webster ]

‖n. [ NL., fr. Gr. me`sos middle + &unr_; a glutinous substance. ] (Zool.) A thin gelatinous tissue separating the ectoderm and endoderm in certain coelenterates. -- Mes`o*glœ"al a. [1913 Webster]

a. [ Meso- + Gr. gna`qos jaw. ] (Anat.) Having the jaws slightly projecting; between prognathous and orthognathous. See Gnathic index, under Gnathic. [ 1913 Webster ]

‖n. [ NL. See Meso-, and Hepar. ] (Anat.) A fold of the peritoneum connecting the liver with the dorsal wall of the abdominal cavity. [ 1913 Webster ]

‖n. [ NL., fr. Gr. me`sos middle + &unr_; a horse. ] (Paleon.) An extinct mammal of the Horse family, but not larger than a sheep, and having three toes on each foot. [ 1913 Webster ]

n. [ L. mesolabium, Gr. &unr_;; me`sos middle + &unr_; to take. ] An instrument of the ancients for finding two mean proportionals between two given lines, required in solving the problem of the duplication of the cube. Brande & C. [ 1913 Webster ]

n. [ Gr. me`sos middle. ] (Min.) Same as Thomsonite. [ 1913 Webster ]

n. [ Meso- + -lite. ] (Min.) A zeolitic mineral, grayish white or yellowish, occuring in delicate groups of crystals, also fibrous massive. It is a hydrous silicate of alumina, lime, and soda. [ 1913 Webster ]

n. [ Meso- + logarithm : cf. F. mésologarithme. ] (Math.) A logarithm of the cosine or cotangent. [ Obs. ] Kepler. Hutton. [ 1913 Webster ]

‖n. [ NL. See Meso-, and Metrium. ] (Anat.) The fold of the peritoneum supporting the oviduct. [ 1913 Webster ]

‖n. pl. [ NL.; meso- + mycetes. ] (Bot.) One of the three classes into which the fungi are divided in Brefeld's classification. -- Mes`o*my*ce"tous a. [Webster 1913 Suppl.]

n. (Zool.) A bird having a mesomyodous larynx. [ 1913 Webster ]

a. [ Meso- + Gr. &unr_;, &unr_;, a muscle. ] (Zool.) Having the intrinsic muscles of the larynx attached to the middle of the semirings. [ 1913 Webster ]

‖n. [ NL., fr. Gr. me`son middle, neut. of me`sos, a., middle. ] 1. (Anat.) The mesial plane dividing the body of an animal into similar right and left halves. The line in which it meets the dorsal surface has been called the dorsimeson, and the corresponding ventral edge the ventrimeson. B. G. Wilder. [ 1913 Webster ]

2. (Physics) An elementary particle made up of two quarks; a hadron having a baryon number of zero; any hadron other than a baryon. Mesons are bosons with integral values of spin, having a mass intermediate between those of the electron and a nucleon; they may have positive or negative charges, or may be neutral. Mesons are of three types: the pion (π-meson), kaon (K-mesons), and η-mesons. [ PJC ]

mu meson (Physics) the former name for the muon, a particle which is not a true meson{ 2 }. The term is no longer used in technical literature, except historically. [ PJC ]

a. [ Meso- + nasal. ] (Anat.) Of or pertaining to the middle portion of the nasal region. [ 1913 Webster ]

a. (Anat.) Of or pertaining to the mesonephros; as, the mesonephric, or Wolffian, duct. [ 1913 Webster ]

‖n. [ NL., fr. Gr. me`sos middle + nefro`s kidney. ] (Anat.) The middle one of the three pairs of embryonic renal organs developed in most vertebrates; the Wolffian body. [ 1913 Webster ]

a. Of or pertaining to a meson. [ PJC ]

‖n. [ NL., fr. Gr. me`sos middle + nw^ton the back. ] (Zool.) The dorsal portion of the mesothorax of insects. [ 1913 Webster ]

‖n. [ NL., fr. Gr. me`sos middle + floio`s bark. ] (Bot.) The middle bark of a tree; the green layer of bark, usually soon covered by the outer or corky layer, and obliterated. [ 1913 Webster ]