1. biosafety level 4 exposure to exotic infectious agents that pose a high risk of life-threatening disease and can be transmitted as an aerosol and for which there is no vaccine or therapy
  2. biosafety level 1 exposure only to infectious agents that do not ordinarily cause human disease
  3. biosafety level 2 exposure to infectious agents that can cause disease in humans but whose potential for transmission is limited
  4. biosafety level 3 exposure to infectious agents that can be transmitted by the respiratory route and which can cause serious infection
  5. biosafety level the level of safety from exposure to infectious agents
  6. poverty level a level of personal income defining the state of poverty
  7. safety valve a valve in a container in which pressure can build up
  8. battlefield a region where a battle is being (or has been) fought
  9. spirit level indicator that establishes the horizontal when a bubble is centered in a tube of liquid
  10. support level (stock market) the price at which a certain security becomes attractive to investors
  11. biosafety safety from exposure to infectious agents
  12. battle flag a flag that leads troops into battle
  13. best-loved preferred above all others and treated with partiality
  14. battleful having or showing a ready disposition to fight
  15. bottleful the quantity contained in a bottle
  16. safety device a device designed to prevent injury or accidents
  17. safety belt belt attaching you to some object as a restraint in order to prevent you from getting hurt
  18. noise level the amplitude level of the undesired background noise
  19. beef tallow tallow obtained from a bovine animal
  20. bass fiddle largest and lowest member of the violin family