invaginate

US: (v. in vaj′ə nāt′; adj. in vaj′ə nit, -nāt′)

WordReference Random House Unabridged Dictionary of American English © 2025

in•vag•i•nate  (v. in vaj′ə nāt′;adj. in vaj′ə nit, -nāt′), v., -nat•ed, -nat•ing, adj. 
v.t. 

1. to insert or receive, as into a sheath;
   sheathe.
2. Physiology to fold or draw (a tubular organ) back within itself;
   intussuscept.

v.i. 

3. to become invaginated;
   undergo invagination.
4. to form a pocket by turning in.

adj. 

5. folded or turned back upon itself.
6. sheathed.

• Medieval Latin invāgīnātus, past participle of invāgīnāre to sheathe. See in-², vaginate
• 1650–60

Collins Concise English Dictionary © HarperCollins Publishers::

invaginate verb / ɪnˈvædʒɪˌneɪt/

1. to push one section of (a tubular organ or part) back into itself so that it becomes ensheathed; intussuscept
2. (intransitive) (of the outer layer of an organism or part) to undergo invagination

adjective / ɪnˈvædʒɪnɪt -ˌneɪt/

1. (of an organ or part) folded back upon itself

Etymology: 19th Century: from Medieval Latin invāgīnāre, from Latin in-² + vāgīna sheath

inˈvaginable adjective