fundamentteihin
Fundamentteihin is a Finnish noun form that functions as the illative plural of fundamentti. Fundamentti means foundation, base, or underpinning, in both physical and abstract senses. The illative case marks direction toward or into something; thus fundamentteihin translates roughly as “to the foundations” or “into the foundations” when used with a plural subject or destination.
In terms of related forms, the base is fundamentti; the nominative plural is fundamentit; the illative singular
In non-technical language, speakers typically prefer the words perusteet or perusta when referring to abstract foundations,