Synonyms for Threaten (same or very similar meaning)
WordNet sense 1 (the most important or necessary part of something):
base
WordNet sense 2 (a relation that provides the foundation for something):
footing, ground
WordNet sense 3 (the fundamental assumptions from which something is begun or developed or calculated or explained):
cornerstone, foundation, groundwork, fundament
From the ODE community, based on WordNet
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