This is the 8769th most frequent Russian word.
пограничной
"Border" or "borderline" (adjective).
indicating something related to a border area
Войска были размещены в пограничной зоне.
The troops were stationed in the border area.
referring to a metaphorical or transitional aspect, here in psychology
Мы обсудили проблемы пограничной психологии.
We discussed the issues of borderline psychology.
denoting something that is at the boundary or on the edge