On the top of. / On the top, with "of".

(literary or archaic) On, to, or at the top.

(medicine) Pertaining to or suffering from atopy.

Atopic; relating to or having atopy.

Not topical; untopical.

(pathology) An atopic, hereditary, and non-contagious skin disease characterized by chronic inflammation of the skin.

(medicine) A hereditary disorder marked by the tendency to develop localized immediate hypersensitivity reactions to allergens such as pollen, food etc and is manifested by hay fever, asthma, or similar allergic conditions; generally considered to be caused by the interaction of environmental and genetic factors.

plural of atopy

(zoology) Any of the extinct reptiles in the family Atoposauridae.

plural of atoposaurid