The term 'ADULT NIT' is a combination of two words, 'ADULT' and 'NIT'. An ADULT NIT is a LOUSE that has reached maturity and is capable of reproducing. ADULT nits are the most common form of lice found on humans and can cause itching and irritation. They are usually found in the hair and scalp, but can also be found on other parts of the body. Treatment for ADULT nits typically involves using medicated shampoos or lotions to kill the lice.