We found 4 dictionaries that define the word third eyelids:

General (2 matching dictionaries)

1. third eyelids: Collins English Dictionary
2. third eyelids: TheFreeDictionary.com

Medicine (2 matching dictionaries)

3. third eyelids: Merriam-Webster Medical Dictionary
4. third eyelids: Medical dictionary

(Note: See third_eyelid as well.)

Definitions from WordNet (third eyelid) ▸ noun:  a protective fold of skin in the eyes of reptiles and birds and some mammals ▸ Also see third_eyelid ▸ Words similar to third eyelids ▸ Usage examples for third eyelids ▸ Idioms related to third eyelids ▸ Wikipedia articles (New!) ▸ Words that often appear near third eyelids ▸ Rhymes of third eyelids ▸ Invented words related to third eyelids