Classical Arabic - English Dictionary

رَثْوٌ Milk such as is termed رَثِيْئَةٌ. (M, Ḳ. [See the latter word, in art. رثأ.])

مَرْثُوٌّ, meaning A man weak in intellect, is from الرَّثْيَةُ, [mentioned in art. رثى,] and [therefore] by rule should be مَرْثِىٌّ. (M.) And مَرْثُوْءٌ [signifies the same, (see this word, in art. رثأ,) and in like manner, accord. to ISd,] is from الرَّثْيَةُ, irreg., being with ء (M in art. رثى.)