1910年,醫學拉丁語,指“智力最低的弱智人羣之一”,源自希臘語(雅典方言)mōron,中性形式爲 mōros,意爲“愚蠢的,遲鈍的,愚笨的”,其起源不確定。與梵語 murah “白癡”(見 moratorium)的聯繫存在爭議。拉丁語 morus “愚蠢的”是從希臘語借來的詞。
被美國弱智研究協會採用,作爲技術定義指“智力年齡在8歲至12歲之間的成年人”; 自1922年以來被用作侮辱性詞彙,並隨後從技術用語中刪除。林奈引入了 morisis “白癡”一詞。
The feeble-minded may be divided into: (1) Those who are totally arrested before the age of three so that they show the attainment of a two-year-old child or less; these are the idiots. (2) Those so retarded that they become permanently arrested between the ages of three and seven; these are imbeciles. (3) Those so retarded that they become arrested between the ages of seven and twelve; these were formerly called feeble-minded, the same term that is applied to the whole group. We are now proposing to call them morons, this word being the Greek for "fool." The English word "fool" as formerly used describes exactly this grade of child—one who is deficient in judgment or sense. [Henry H. Goddard, in "Journal of Proceedings and Addresses" of the National Education Association of the United States, July 1910]
弱智人羣可以分爲:(1)在三歲之前完全停滯不前,表現出兩歲以下兒童的能力; 這些人是白癡。(2)那些在三歲至七歲之間永久性停滯的人; 這些人是低能兒。(3)那些在七歲至十二歲之間停滯的人; 這些人以前被稱爲弱智,這個術語適用於整個羣體。我們現在打算稱他們爲 morons,這個詞是希臘語中的“傻瓜”。英語單詞“fool”曾經準確地描述了這個兒童的等級——一個在判斷或感覺方面有缺陷的孩子。[亨利·H·戈達德(Henry H. Goddard),於1910年7月在美國全國教育協會的“會議和演講記錄”中]