This is the 11666th most frequent French word.
saper
To undermine or weaken.
In this sentence, 'saper' is used in its figurative sense, meaning to undermine or weaken someone's authority or credibility, often in a subtle or indirect manner.
Il a essayé de saper mon autorité devant l'équipe.
He tried to undermine my authority in front of the team.
In this context, 'saper' is employed literally, indicating the action of causing structural weakening or harm to a physical object (the building's foundations in this case).
Les racines des arbres sapent les fondations du vieux bâtiment.
The tree roots are undermining the foundations of the old building.
Here, 'saper' conveys the idea of making something invalid or ineffective, specifically a rule or regulation, through deliberate actions.