Heard spelling

jynoecium

Spelled gynoecium. a soft g

It sounds like it starts with a j.

It does, and it is still spelled with a g.

This is the closest anyone gets by ear alone. Every other letter in jynoecium is already correct: the y from gyne, the oe from oikos, the soft c before i, the Latin -ium ending. Only the first letter is wrong, and it is wrong for a reason that has nothing to do with sound. Greek gamma is transliterated g in English, always, whatever happens to it afterwards in speech. The same rule holds the g in gymnasium, gyrate, gypsum and gynaecology, every one of them said with a soft g and none of them spelled with a j.

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