• weed
  • Any plant that grows wild and profusely, especially one that grows among cultivated plants, depriving them of space, food, etc.
Abstract from DBPedia
    A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted. This introduces the concept of humans and their goals in a particular setting. The concept of weeds is particularly significant in agriculture, where the aim is growing crops or pastures of a single species, or a mixture of a few desired species. In such environments, other plant species are considered undesirable and therefore a weed. Besides, some weeds have undesirable characteristics making them a plant pest in most human settings. Examples of weeds are plants unwanted in human-controlled settings, such as farm land, orchards, gardens, lawns, parks, residential and industrial areas. Taxonomically though, the term "weed" has no botanical significance, because a plant that is a weed in one context, is not a weed when growing in a situation where it is wanted. In the same way, volunteer plants are regarded as weeds in a subsequent crop. Some plants that are widely regarded as weeds are intentionally grown in gardens and other cultivated settings, in which case they are sometimes called beneficial weeds. The term weed is also applied to any plant that grows or reproduces aggressively, or is invasive outside its native habitat. More broadly, the term "weed" is occasionally applied pejoratively to species outside the plant kingdom, species that can survive in diverse environments and reproduce quickly; in this sense it has even been applied to humans. Weed control is important in agriculture. Methods include hand cultivation with hoes, powered cultivation with cultivators, smothering with mulch or soil solarization, lethal wilting with high heat, burning, or chemical attack with herbicides and cultural methods such as crop rotation and fallowing land to reduce the weed population.

    雑草(ざっそう)の定義は主に社会学的なものと生物学的なものに分けられる。社会学的な考えでは、農耕地などで作物以外の、人の意図にかかわらず自然に繁殖する植物、景観を損ねる所に生える人に望まれない植物など、間接的、直接的に損害を与える所に生える植物のことを指す場合が多い。社会学的な雑草の定義は個々の人間の主観、価値観により変わり、どの種が雑草であるかの定義も人それぞれである。生物学的定義では雑草とは「土壌攪乱に対応した植物を指す」とされ、種子が不良な温度変化、湿度変化に耐え、休眠状態で死滅せずに土壌中に深くに保存され、その後に耕しなどの人為要因や、降雨降雪などの自然要因により土壌が攪乱され、種子が土壌表層に持ち上げられ自然に発芽し育った、その場に生える植物のことを指す。 生物学において人里や河川敷に自然に生える植物は雑草と定義される(その他、狭義の定義については雑草#定義を参照)。通常、草(草本)についていう。雑草を単に草という場合もある(除草、草刈りなど)。

    (Source: http://dbpedia.org/resource/Weed)