The first occurrence.
And God said, “Let the waters bring forth abundantly the living creature that has life, and winged creatures that may fly above the earth in the open firmament of heaven.” Gen 1:20
The primitive root.
ayin ע = the eye, thus watch, know, shade
vav ו = the tent peg, thus add, secure, hook
pey פ ף = the mouth, thus open, blow, scatter, edge
According to the Ancient Hebrew Lexicon, cognate words for “to fly” are “wing,” “foliage,” “eyelid,” and “branch,” with the common meaning of something that covers. To be shaded (ayin) is also to be covered. And if you look at a photo of baby birds, their most prominent characteristic is their open mouths. So that led me to think of the saying of Yeshua:
“O Jerusalem, Jerusalem, the one who kills the prophets and stones those who are sent to her! How often I wanted to gather your children together, as a hen gathers her chicks under her wings, but you were not willing!” Mat 23:37
When a hen gathers her chicks, her baby birds, she covers them with her wings. The story: That which shades (ayin) securely (vav) the open mouth (pey, i.e. the baby birds), thus wing, the instrument of flight.