Very basic or simple; in an early or undeveloped stage, containing only the most essential elements.
From Latin 'rudimentum' meaning beginning or first attempt; from 'rudis' meaning raw or unformed, ultimately related to 'ruddy' (reddish, like raw flesh).
Humans have rudimentary muscles around our ears and noses that other animals use constantly—we've basically abandoned them, which is why moving your ears impresses people but cats do it automatically.
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