I thought it was endoplasmic recticulum with an um... but then what do I know I'm a mediocre student.:rolleyes2
Reticulum is the singular form. Reticula is the plural. It's a Latin 2nd declension neuter noun and a diminuative form of the word that means "bag" or "net."
Or maybe it's the Latin word for "kryptonite." I seem to have forgotten.