I use the terms “primary” and “secondary” to talk about degrees of life entanglement. For me, a primary is like a spouse or partner – someone you live with and share major decisions with. A secondary is like a boyfriend or girlfriend – doesn’t mean you love them less but you probably have separate finances and living space.
With that being said I don’t usually say “My secondary X…” I just say boyfriend, or girlfriend, or sweetheart, or whatever.
I have also seen – and like – the terms “domestic” and “feral” poly to talk about whether you have a live-in relationship.