This is the 1802nd most frequent Russian word.
крайней
"Крайней" means "extreme" or "outermost" in English, depending on context.
The word 'крайней' is used here in the idiomatic phrase 'в крайней мере', meaning 'at the very least'.
В крайней мере, он старался помочь.
At the very least, he tried to help.
The word 'крайней' describes the position of the village as the last or extreme one in proximity to the forest.
Она живёт в крайней деревне перед лесом.
She lives in the last village before the forest.
The word 'крайней' refers to a critical or extreme need in this context.