A few butterflies and many moth species spin a silk case or cocoon prior to pupating, while others do not, instead going underground. A butterfly pupa, called a chrysalis, has a hard skin, usually with no cocoon.
4. tension - (physics) a stress that produces an elongation of an elastic physical body; the direction of maximum tension moves asymptotically toward the direction of the shear. natural philosophy, physics-the science of matter and energy and their interactions; his favorite subject was physics.
tension(Noun) Force transmitted through a rope, string, cable, or similar object (used with prepositions on, in, or of, e.g., The tension in the cable is 1000 N, to convey that the same magnitude of force applies to objects attached to both ends). tension(Noun) Voltage.