Short Circuit Output Current - IC Definitions
These are Rail-to-Rail I/O, CMOS Amplifiers.

Datasheet indicates Vs=5V. In this context, short-circuit implies operating the CMOS FET outputs with RdsOn at any output voltage rail to rail.

Thus +/-33 mA means RdsOn = 5V/33mA = 150 Ohms typical equivalent resistance.  This affects the output rise time for step pulses into a know C load.  However when not shorted, Zout is reduced by feedback gain in linear mode.

added: 


Under different conditions the table also says;    
RL=10k to Vs/2 (for Vs=5V)  Vo= 0.01 to 4.99V   I=250uA, thus RdsOn=40  
RL=1k to Vs/2 (for Vs=5V)  Vo= 0.10 to 4.90V    I=2.5mA  thus RdsOn=40 


proof by Simulation

Using KVL as follows;







simulate this circuit &ndash; Schematic created using CircuitLab

Only in 3.6V logic do they make lower RdsOn =25 Ohms +/50% in order to shoot-thru and yet have high speed.