Enclosed in a sheath.
Late 18th century; earliest use found in Stephen Robson (1741–1779), botanist. From post-classical Latin vaginatus sheathed from classical Latin vāgīna sheath + -ātus.
To sheathe; specifically to surround (a part of plant) with a sheath. Usually in passive.
Mid 17th century; earliest use found in Thomas Blount (1618–1679), antiquary and lexicographer. From post-classical Latin vaginat-, past participial stem of vaginare to sheathe from classical Latin vāgīna.