- A @M03986@ that forms @C01203@ with organic or inorganic guests, or a chemical species that can accommodate guests within cavities of its crystal structure. Examples include @C01426@ and @C01421@ (where there are ion-dipole attractions between heteroatoms and positive ions), @H02899@ molecules that form '@C01097@' (e.g. hydroquinone and water), and host molecules of @I02998@ (e.g. urea or thiourea). @V06597@ and @H02907@ bind the @G02711@ to the host molecule in @C01097@ and inclusion compounds.
- (in biotechnology) A cell whose @M03858@ is used for growth and reproduction of a virus, @P04689@ or other form of foreign @D01597@.