A group of people all descended from a common ancestor, in fact or belief, especially when the exact genealogies are not known.
"The Highland clan gathered at the ancient cairn to honor their shared lineage despite no written records proving every connection."
In plain English: A clan is a large group of people who are all related to each other and share the same family name.
"The entire clan gathered together to celebrate their ancestor's birthday."
Usage: Use clan to describe large family groups united by shared ancestry and tradition rather than strict legal lineage. This term is often applied to Scottish Highland families but can also refer similarly organized communities elsewhere.
The word clan comes from the Irish clann, meaning "offspring" or "children of the family." It traveled into English through Scottish Gaelic and ultimately traces its roots back to the Latin planta.