Rashi had ten methods to explain biblical meaning.
Rashi would sometimes derive the meaning of a word from the meaning
of its underlying Biblical root. Today's example illustrates this.
Sarah's skepticism at having a child states
....after my menopause I will have periods.
An literal translation of the same verselet would be
....after my withering I will have delights.
The Hebrew word
female youth, (pre-menopause)
grammatically comes either from the root
or from the root
In other words Rashi advances the idea that
Youth / pre-menopause is the time of delight, pleasure.
Similarly, Rashi advances the idea that
Pre-menopause is the time of periods,dates, and times.
Advanced Rashi: Very often etymologies come in pairs. The idea is
that even if a word had a primary etymology it very often by puns and inuendos achieves
secondary etymologies. After a while both derivations become equally important.