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Synonyms for Flat-footed (same or very similar meaning)

WordNet sense 1 (not prepared or in a state of readiness; slow to understand or respond):
unready

WordNet sense 2 (having feet that turn outward):
splayfoot, splayfooted

WordNet sense 3 (having feet):
footed

WordNet sense 4 (extended senses; direct in means or manner or behavior or language or action):
direct


From the ODE community, based on WordNetadd/edit