noun Download 🔗Share Any of free-swimming pelagic sea snails and sea slugs, of the suborder Thecosomata, that have winglike lobes on the feet; a sea butterfly. Examples : "While snorkeling in the clear blue water, we saw a tiny, almost transparent pteropod fluttering its wing-like feet as it swam past. " animal ocean biology nature organism fish Chat with AIVocabulary GamePractice Reading