Heard spelling

jynoecum

Spelled gynoecium. two changes at once

What is missing from jynoecum?

The g at the front and the i before the final m. Gynoecium has nine letters; jynoecum has eight.

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