4. Undefined Terms M Has infinite length and width but no thickness; is a flat surface Single capital letter Read: Plane M Slanted four-sided figure Plane Has infinite length but no width and thickness; is straight Two capital letters with a double arrowhead above them or a lower case letter Straight mark with two arrow heads Line Has no length, width or thickness; occupies no space • P Read: point P Dot • Point Other Information How to name? Picture Undefined Term