From Longman Dictionary of Contemporary Englishsacsac /sæk/ noun [countable] technical HBPHBAa part inside a plant or animal that is shaped like a bag and contains liquid or air
Examples from the Corpus
sac• Be sac and write your story step by step.• The child slipped into the world, still in its birth sac.• The tip of the catheter was positioned directly on the gestational sac.• With these different theories come different conclusions about the history of the skeleton, fins, nasal sacs and so on.• Then he lifted something small and wet; a pale, tiny sac attached by tubes and tendons to the rest.Origin sac (1700-1800) French “bag”, from Latin saccus; → SACK1 