Ma'anar ƙamus na kalmar "polysomy" shine yanayin samun fiye da chromosomes guda biyu a cikin tsakiya na tantanin halitta. Kalma ce da ake amfani da ita a cikin kwayoyin halitta don bayyana yanayin da kwayoyin halitta ke da guda ɗaya ko fiye da ƙarin kwafi na wani chromosome ko chromosomes, fiye da lambar diploid na al'ada. Polysomy na iya faruwa ta dabi'a, ko kuma yana iya haifar da shi ta hanyoyi daban-daban na kwayoyin halitta ko abubuwan muhalli.