(1) Does the definition include all the parallelograms? Yes. Does it exclude all other quadrilaterals? Yes. Are there any unnecessary marks? No.
(2) Does it include all birds? Yes. Does it exclude all other bipeds? Yes. Any unnecessary marks? No.
Illogical According to the Second Rule.
(1) A man is a vertebrate animal.
(Too broad. Does not exclude other species of the genus, such as horses, dogs, etc.)
(2) A barn is a building where horses are kept.
(Too narrow. Does not include all of the species, such as cow barn.)
(3) An equilateral triangle is a triangle all of whose sides and angles are equal.
(Equal angles is an unnecessary mark.)
The Foregoing Definitions Made Logical.