Obliquely. That which differs from a right angle; neither obtuse nor acute; deviating from a line by any angle except a right angle.
Obvious. That which is readily observed and understood.
Orthopter. That type of flying machine which depends on flapping wings to hold it in space, and to transport it, in imitation of the motion of the wings of birds in flying.
Oscillate. Moving to and fro; the piston of a steam engine has an oscillating motion.
Outline. Describing a marginal line on a drawing; setting forth the principal features of an argument, or the details of a story, or the like.
Overlapping. One placed over the other.
Parabolic. A form of curve somewhat similar to an ellipse.
Pedestal. A standard or support; an upright to hold machinery.
Pertinent. Appropriate; pertaining to the subject.
Pectoral. The bone which forms the main rib or support at the forward edge of a bird's wing.