[化] 内消旋; 中; 中间; 中(位)(即蒽环核的9,10位); 介; 新

[医] 正中, 中间, 中位, 内消旋, 新(化学)

Meso- \Mes"o-\, Mes- \Mes-\ [Gr. me`sos in the middle.]
1. A combining form denoting in the middle, intermediate.

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

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]