Heard spelling

gineecium

Spelled gynoecium. two changes at once

Why oe rather than ee?

Because the syllable is the Greek word for house, oikos, and Latin wrote Greek oi as oe.

Gineecium spells that syllable by ear and loses the seam. Once you can see that the second half is oikos, the same join shows up in androecium, and in a much older borrowing: economy was oikonomia, the management of a house, and English wrote it oeconomy for a long time before wearing the o off.

Say

guy-NEE-see-um, and jy-NEE-see-um is heard just as often

Letters

G-Y-N-O-E-C-I-U-M