[n. lous; v. lous, louz] 
noun, plural lice [lahys] for 1–3, lous⋅es for 4, verb, loused, lous⋅ing.| 1. | any small, wingless insect of the order Anoplura (sucking louse), parasitic on humans and other mammals and having mouthparts adapted for sucking, as Pediculus humanus (body louse or head louse) and Phthirius pubis (crab louse or pubic louse). |
| 2. | any insect of the order Mallophaga (bird louse, biting louse, or chewing louse), parasitic on birds and mammals, having mouthparts adapted for biting. |
| 3. | plant louse. |
| 4. | Slang. a contemptible person, esp. an unethical one. |
| 5. | to delouse. |
| 6. | louse up, Slang. to spoil; botch: Miscasting loused up the movie. |
louse (lous)
n. pl. lice (līs)
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.
louse up
Spoil, ruin, bungle. For example, The bad weather loused up our plans, or Your change of mind really loused me up. This slangy expression originated in World War I, when infestation with lice was the common lot of soldiers in the trenches; its figurative use dates from the 1930s.