What's the "een" in Halloween?
1650s, "a ghost, specter," from Latin larva (plural larvae), earlier larua "ghost," also "mask;" applied in biological sense 1768 by Linnaeus because immature forms of insects "mask" the adult forms. On the double sense of the Latin word, Carlo Ginzburg, among other students of mythology and folklore, has commented on "the well-nigh universal association between masks and the spirits of the dead."
larva lar·va (lär'və)
n. pl. lar·vas or lar·vae (-vē)
The newly hatched, wingless, often wormlike form of many insects before metamorphosis.
The newly hatched, earliest stage of any of various animals that undergo metamorphosis, differing markedly in form and appearance from the adult.
Plural larvae (lär'vē) or larvas
in Roman religion, wicked and fearsome spectres of the dead. Appearing in grotesque and terrifying forms, they were said to haunt their living relatives and cause them injury. To propitiate these ghosts and keep them from the household, ritual observances called Lemuria were held yearly on May 9, 11, and 13. These Lemuria, reputedly instituted by Romulus in expiation of his brother's murder, required the father of every family to rise at midnight, purify his hands, toss black beans for the spirits to gather, and recite entreaties for the spirits' departure.