1. (n.)louse any of various small, flat, wingless insects of the order Anoplura, with sucking mouthparts, that are parasitic on humans and other mammals, as Pediculus humanuscapitis
2. louse any similar insect of the order Mallophaga, with biting mouthparts, parasitic on birds and some mammals.
Etymology: (bef. 900; ME lous(e),luse, OE lūs, c. MD, MLG, OHG, ON lūs)
Definition of 'louse'
Princeton's WordNet
1. (noun)louse, sucking louse wingless usually flattened bloodsucking insect parasitic on warm-blooded animals
2. (noun)worm, louse, insect, dirt ball a person who has a nasty or unethical character undeserving of respect
3. (noun)plant louse, louse any of several small insects especially aphids that feed by sucking the juices from plants
4. (noun)bird louse, biting louse, louse wingless insect with mouthparts adapted for biting; mostly parasitic on birds
Definition of 'louse'
Webster Dictionary
1. (noun)louse any one of numerous species of small, wingless, suctorial, parasitic insects belonging to a tribe (Pediculina), now usually regarded as degraded Hemiptera. To this group belong of the lice of man and other mammals; as, the headlouse of man (Pediculus capitis), the bodylouse (P. vestimenti), and the crablouse (Phthirius pubis), and many others. See Crab louse, Dog louse, Cattle louse, etc., under Crab, Dog, etc
2. (noun)louse any one of numerous small mandibulate insects, mostly parasitic on birds, and feeding on the feathers. They are known as Mallophaga, or bird lice, though some occur on the hair of mammals. They are usually regarded as degraded Pseudoneuroptera. See Mallophaga
3. (noun)louse any one of the numerous species of aphids, or plant lice. See Aphid
4. (noun)louse any smallcrustacean parasitic on fishes. See Branchiura, and Ichthvophthira
Definitions of louse 
Afrikaans: luis
Arabic: قَمْلَه
Bulgarian: въшка
Brazilian: piolho
Czech: veš
German: die Laus
Danish: lus
Greek: ψείρα
Spanish: piojo
Estonian: täi
Farsi: شته؛ شپش
Finnish: täi
French: poux
Hebrew: כִּינָה
Hindi: जू
Croatian: uš
Hungarian: tetű
Indonesian: kutu
Icelandic: lús
Italian: pidocchio
Japanese: しらみ
Korean: 진딧물
Lithuanian: utėlė
Latvian: uts
Malay: kutu
Dutch: luis
Norwegian: lus
Polish: wesz
Persian: شپش
Pashto: سپږه،شپګه
Portuguese: piolho
Romanian: păduche
Russian: вошь
Slovak: voš
Slovenian: uš
Serbian: vaška
Swedish: lus
Thai: แมลงเล็ก ๆ ที่อยู่บนคนและ
Turkish: bit
Taiwanese: 蝨子
Ukrainian: оша
Urdu: سر کے بالں اور جلد میں پڑ
Vietnamese: rận; chấy
Chinese: 虱子
