Ma'anar ƙamus na kalmar "nosology" shine reshe na kimiyyar likitanci wanda ya shafi rarrabuwar cututtuka. Nazarin rarrabuwa ne, rarrabuwa, da bayanin tsari na cututtuka ko yanayin likita. Nosology ya ƙunshi ganowa da ma'anar cututtuka daban-daban da tsara su zuwa rukuni bisa ga halaye masu alaƙa, kamar alamomi, sanadi, da jiyya. Yana da muhimmin fanni na nazari ga kwararrun likitocin, domin yana taimaka musu wajen gano cututtuka da kuma magance cututtuka daban-daban yadda ya kamata.