vesicle

Concise Oxford English Dictionary © 2008 Oxford University Press:
vesicle /ˈvɛsɪk(ə)l, ˈviː-/

▶noun

• 1 Anatomy & Zoology a small fluid-filled sac or cyst within the body.

  ■ Medicine a blister full of clear fluid.

• 2 Botany an air-filled swelling in a seaweed or other plant.

• 3 Geology a small cavity in volcanic rock, produced by gas bubbles.

– derivatives
vesicular adjective,
vesiculated adjective,
vesiculation noun.

– origin C16: from Fr. vésicule or L. vesicula, dimin. of vesica ‘bladder’.