I’ve seen ‘Active / Passive’ used, that seems alright

That’s not always an accurate description though.

Consider a redundant two node database system where the second node holds a mirrored copy of the first node. Typically, one node, let’s call it node1, will accept reads and writes from clients and the other node, let’s say node2, will only accept reads from clients but will also implement all writes it receives from node2. That’s how they stay in sync.

In this scenario node2 is not “passive”. It does perform work: it serves reads to clients, and it performs writes, but only the writes received from node1. You could say that node2 slavishly follows what node1 dictates and that node1 is authorative. Master/slave more accurately describes this than active/passive.

There’s plenty of alternative terms to use without borrowing terminology from sexual roleplay.

Do I have news for you …