In relation to gender equality, horizontal segregation refers to the concentration of women and men in different sectors and occupations. It is understood as under- or overrepresentation of women or men in occupations or sectors, not ordered by any criterion. This contrasts with vertical segregation, which concerns the top of an ordering based on ‘desirable’ attributes such as income, prestige, etc.
See also: vertical segregation
(1) European Commission (1998). 100 Words for Equality: A Glossary of Terms on Equality between Women and Men; (2) Bettio, F., and Verashchagina, A. (2009). Gender Segregation in the Labour Market: Root Causes, Implications and Policy Responses in the EU.