noun

1. a losing or being lost
2. an instance of this
3. the damage, trouble, disadvantage, deprivation, etc. caused by losing something
4. the person, thing, or amount lost
5. any reduction, lessening, etc. a loss of strength, power, etc.
6. any reduction of heat energy, electrical energy, etc. in a system, esp. the reduction of power, voltage, or current in a circuit due to the resistance of the components
7. Insurance
   1. death, injury, damage, etc. that is the basis for a valid claim for indemnity under the terms of an insurance policy
   2. the amount paid by the insurer on this basis
8. Mil.
   1. the losing of military personnel in combat by death, injury, or capture
   2. those lost in this way
   3. ships, aircraft, etc. lost in battle

Etymology: ME los < pp. of losen, lesen, to lose