hypojimnia: two letters out
heard as hypojimnia
spelled hypogymnia
The j is a g and the i is a y. Hypogymnia.
What the ear did
Both errors come from the same source, which is the soft g. Once a reader writes j, the y that softened the g has nothing left to do, so it turns into an i as well.
H-Y-P-O-G-Y-M-N-I-A
The full entry for hypogymnia covers the name itself.