(chemistry) a crystalline solid consisting of a host lattice containing voids into which guest atoms or molecules are inserted

(chemistry) a macrocycle

(chemistry) any compound in which a metal atom is located between the faces of two planes of atoms, especially between two rings

(chemistry) a substance consisting of molecules of one element or compound contained within the cage-like structure of another

(chemistry) any of a class of compounds having five-membered ring heterocycles (or their benzo derivatives) which possess a sextet of π-electrons in association with the atoms comprising the ring, but which cannot be represented by any one covalent or polar structure; typically the ring structure contains both positive and negative delocalised charges which cannot be associated with any one ring atom, and the negative charge can also be associated with a conjugated exocyclic atom (typically oxygen, sulfur, or nitrogen).

(organic chemistry) Any compound which exhibits aromaticity.

(chemistry) Any compound containing a cation of general formula R₄As⁺; the arsenic analogue of quaternary ammonium compounds.

(chemistry) Any compound having two or more rings interconnected like the links of a chain, without a covalent bond.

(obsolete, organic chemistry) Synonym of oxime

(organic chemistry) Any polycyclic compound having a single atom (usually carbon) as the only common member of two rings.