A narrow or obstructed section, as of a highway or a pipeline. A point or an area of traffic congestion. A hindrance to progress or production. The narrow part of a bottle near the top. Music A style of guitar playing in which an object, such as a piece of glass or metal, is passed across the strings to achieve a gliding sound. Biology An abrupt and severe reduction in the number of individuals during the history of a species of a population, often resulting in the loss of diversity from the gene pool.