In this paper we introduce a concept of skewness and suggest its measure among a class of unimodal distributions. The measure is built on the lack of symmetry of the density function around the the mode of the distribution. It is shown to satisfy all standard properties expected from a measure of skewness, including location and scale invariance. The extreme values of the measure are characterized. Although the measure is defined for a relatively narrow class of distributions, its utility is established by showing that it is applicable for most popularly used contimuous distribution families.