Head Lice Glossary

Head lice The infestation of the human scalp with the parasitic insect, lice. Also referred to as pediculosis.
Lice Any of numerous small, flat-bodied, wingless biting or sucking insects of the orders Mallophaga or Anoplura, many of which are external parasites on various animals, including humans. Can include the categories of pubic lice, body lice or head lice. In referring to lice, louse is the singular form, lice is the plural form.
Lice nymphs In the 3-part life cycle of head lice, the nymph stage is the second stage. After the nit hatches, the nymph stage, takes about 7-10 days. The nymph typically molts 3 times before reaching its adult louse form.
Lindane A white crystalline powder, C6H6Cl6, used chiefly as an agricultural pesticide but also used topically in the treatment of scabies and pediculosis. Often prescribed by doctors under the name Quell®. Lindane has been banned for use in 52 countries and the state of California as it has been linked to seizures, developmental disabilities and hormone disruption.
Louse Any of numerous small, flat-bodied, wingless biting or sucking insects of the orders Mallophaga or Anoplura, many of which are external parasites on humans. In referring to head lice, louse is the singular form, lice is the plural form.
Nit The egg or young of a parasitic insect, such as a louse. Nits are the first stage of the 3-part life cycle of head lice. The word nit can be used interchangeably with egg.
No-Nit Policy Some schools adapt a no-nit policy which means a child may not return to school until all lice and nits have been removed from their hair.
Non-toxic Literally translated, "not toxic". Not producing or resulting from poison. Licefreee! Pediculicide is classified as a non-toxic product.
Pediculicide An agent used to kill head lice, body lice or pubic lice. Most commonly used ingredients in pediculicides are permethrin, pyrethrum, and lindane. Non-toxic pediculicides, such as Licefreee!, are also available.
Pediculosis The infestation of the human scalp, body or pubic area with lice. Most often referred to as head lice.
Permethrin A topical insecticide, C21H20CL2O3, used to treat head lice and nits, scabies, and various species of ticks. Permethrin is the active ingredient used in the over-the-counter lice treatment, Nix®.
Pyrethrum An insecticide made from the dried flower heads of Chrysanthemum cinerariifolium or C. coccineum. Most often used for the treatment of head lice, nits and scabies. Pyrethrum is the active ingredient used in the over-the-counter product, Rid®.