What is large signal voltage gain (Av) of an operational amplifier?

Also known as open voltage (no negative feedback) gain, large signal voltage gain is used in data sheets to show the differential voltage gain in direct current. A value of around 100 dB (x100,000) is standard for an operational amplifier.
The Av vs. f characteristics in the general-purpose operational amplifier uPC151 are shown below. Note how the Av value tends to decrease as the frequency increases.