how to understand dropout voltage in LDO datasheet?

Hello,

Recently I have a problem about dropout voltage. I need ADP1741 to output 1.8V,the dropout voltage from ADP1741 datasheet is 280mV max,Iout=2A. Does it mean my Vin mustnot exeed 2.08V?so I cannot understand real mean about "dropout voltage".How to meet the dropout voltage in my design?Vin-Vout greater than dropout voltage or Vin-Vout less than dropout voltage,which one can make the chip ADP1741 work normally? 

thank you very much