also: なりなんとす
expression
to be about to reach (an age, state, etc.); to be on the verge of
Archaic expression meaning 'to be on the point of reaching' a certain age, condition, or stage. Often used in classical literature. The form 垂んとする is a variant.
See also: 垂んとする
彼は五十に垂んとす。
He is about to turn fifty.
日は暮れなんとす。
The day is about to end.
A variant of 垂んとす with the same meaning; 垂んとす is the classical sentence-ending form, while 垂んとする is the attributive form.
Classical Japanese phrase from 垂る (to hang down, to be about to) + auxiliary ん (volitional/conjectural) + とす (to do). The kanji 垂 is used for its meaning of 'hanging down' or 'approaching'.