the cocoon cocoon noun a silky protective envelope secreted by silkworms and certain other insect larvae , in which the pupae develop a similar covering for the eggs of the spider , earthworm , etc a protective spray covering used as a seal on machinery a cosy warm covering verb to wrap in a cocoon gouts decrepit corpse lay belly up across his dishevelled bed , like some kafkaesque nightmare , with a hand towel wrapped around his pencil like waist ; he had just taken his last shower .