mun

The root mun comes from Latin mūnus, a word with a surprisingly social meaning. A mūnus was a duty owed to your community — a public office, a service you performed for the group — but it also meant the gift you exchanged as part of that bond. In Roman life, duty and gift were two faces of the same coin: you owed your city service, and you gave gifts to bind people together. Keep both senses in mind — duty and gift — because every word in this family grows out of one or the other.

The most important branch starts with the adjective commūnis = com- ('together') + mūnis ('sharing the duties'). Something commūnis is what everyone shares the burden — and the benefit — of. That gives us:

- common — shared by everyone, belonging to all (this is commūnis itself, not related to mon 'to warn')
- community — the body of people who share that common life
- communal — belonging to the group, held in common
- communicate — literally to make common, to put an idea into the shared space so others have it too. When you communicate, you don't lose the idea; you share it — exactly like a gift that can be given without being given up.
- communism / communist — the political idea that property should be held in common

The second branch keeps the bare mūnus = duty. Add the prefix in- ('not, free from') and you get immūnis — free from duty. In Rome, an immūnis person was exempt from public service or taxes. Centuries later, doctors borrowed the word: a body immune to a disease is one that the disease can't 'charge' anymore — it's been exempted. So:

- immune — exempt; (medically) protected, the disease can't claim you
- immunity — that exemption, whether legal (diplomatic immunity) or biological
- immunize — to grant that exemption against a disease

The third branch keeps mūnus = gift. Combine it with facere ('to make, do') and you get munificent — literally gift-making, hence lavishly generous; the quality is munificence. And re- ('back') + mūnus gives remunerate ('to gift back, to pay'), so remunerative work is work that pays you back well.

The whole family hangs together once you see the link: a mūnus is what you owe to and exchange within a group. Share that duty → common, community, communicate. Be released from it → immune. Turn it into a gift → munificent, remunerative.