This is the 6897th most frequent Dutch word.
achterliggende
"Underlying" or "behind something (in purpose or reason)."
In this context, the word 'achterliggende' is used as an adjective to describe 'reden' (reason), indicating the reason that lies behind or underlies something.
De achterliggende reden voor zijn beslissing is niet duidelijk.
The underlying reason for his decision is not clear.
Here, 'achterliggende' modifies 'tijd' (time), referring to a time that is behind, as in the past.
De achterliggende tijd was moeilijk voor hen.
The past period was difficult for them.
In this sentence, 'achterliggende' qualifies 'structuur' (structure), meaning the structure that is beneath or foundational.