I recently found in my dictionary the triple: проща́ться (нв.), прости́ться (св.), попроща́ться (св.), for to say goodbye.
What do the two imperfective forms mean here in particular?
Is there a general scheme for the meaning in such cases where there are two perfective forms not only differing by a prefix?
Проститься often means to say goodbye forever or for a long time. Sometimes it refers to the custom of asking forgiveness before taking one's leave.
Они простились с усопшим.
Мы простились и он уехал (far away and for a long time).
Прощаться (попрощаться) means to say goodbye before parting for a short period of time. Sometimes it may be applied in the case of parting for a long time or forever.
мы попрощались. (and we will see each other tomorrow or soon)
"Прости́ться" in the meaning of "saying goodbye" is considered archaic in modern Russian where "попроща́ться" would be used instead. For example:
Царь с царицею простился,
В путь-дорогу снарядился,
И царица у окна
Села ждать его одна.
In the modern language, the first line would be expressed as "царь с царицей попрощался". "Прости́ться" can still be used when saying goodbye forever — like leaving for good or a final farewell to the deceased.
