Avoid unnecessary definitions . The main purpose of a definition is to achieve clarity without needless repetition. Do not define in a way that conflicts with ordinary or accepted usage . If possible, use a word in a way that is consistent with the its everyday meaning and do not define the word. Otherwise, you confuse the reader and risk using the word elsewhere in your regulations in its ordinary sense.
Aircraft means a device that is used or intended to be used for flight.
Do not define a term that is used only once or infrequently . If a term is used only once or infrequently, spell out the meaning of the term at those few places it appears in the regulations. Do not include part or all of the term being defined in the text of your definition . A true definition should not include the term being defined as part of the definition. This forces the reader to consult a dictionary or look elsewhere in the regulations for the complete meaning.