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1. Of or relating to basic facts or principles; elementary: I have only a rudimentary knowledge of Greek.
2. Being in an early stage of development or having a simple form: traveled upriver in a rudimentary boat.
3. Biology Imperfectly or incompletely developed: a mutant mouse with rudimentary claws.
ru′di·men·tar′i·ly (-târ′ə-lē) adv.
the state or quality of being rudimentary