Initialism of absolute refractory period.
"She plugged her guitar into an external ARP to layer rich, cascading chords over her solo performance."
An arpeggiator.
In plain English: An ARP is an electronic music tool that plays the notes of a chord one after another, instead of all at once.
"The synthesizer's arp created a cascading melody that filled the room."
Usage: Arp (noun) refers to a musical device, either hardware or software, called an arpeggiator that plays the notes of a chord in sequence rather than simultaneously. Think of it as automatically rolling through the notes of a chord one after another.
Initialism of Address Resolution Protocol.
"When I met my new neighbor, he introduced himself as Mr. Arp and told me his family has lived in the area for three generations."
A surname.
The bark of a seal.
"The curious pup climbed over the old arp to reach its mother on the ice floe."