74LS14 datasheet question (Short-circuit output current)
JEDEC defines short-circuit output current as:

short-circuit output current (IOS)
(1) (of a digital integrated circuit)
The current into an output terminal when the output is short-circuited to ground with input conditions applied that, according to the product specification, will establish the output logic furthest from ground potential.
(2) (of an analog integrated circuit):
The output current with the output shorted to ground or other specified point.
References:
JESD99B, 5/07 JESD99B, 5/07

Source: https://www.jedec.org/standards-documents/dictionary/terms/short-circuit-output-current-ios-1-digital-integrated-circuit
You might be interested in I_OS if, for instance, you are driving a relative large capacitive load. Such a load would initially appear as a short to ground when the capacitor is fully discharged.
The TI publication &quot;Designing With Logic&quot; contains a wealth of tips and information that is very helpful when designing with digital logic. Section 6.3 talks about how I_OS is related to the propagation delay time into a capacitive load and the device's output impedance.