heredaĵo

Decoding it. Heredi at rank 1,712 is the verb, to inherit. -Aĵ- is the suffix that turns an action or a quality into a concrete thing produced by it: manĝi gives manĝaĵo food, konstrui gives konstruaĵo a building, bovo gives bovaĵo beef. So a heredaĵo is the thing inherited - the house, the money, the box of letters. Not the act, not the right, the stuff.

Which is exactly why the family needs three words, not one. Heredo is the inheriting itself, the event. Heredaĵo is what comes down to you. Heredanto is the person who inherits, the heir, and heredonto the one who is going to. English collapses most of this into inheritance and lets context sort it out; Esperanto makes you choose, and the choice is made for you by which suffix fits.

The Unesco sense, which is the one you will meet most. Monda heredaĵo is World Heritage, and kultura heredaĵo is cultural heritage - a building, a language, a way of doing something, handed down rather than owned. The movement uses the phrase about itself, and argues about it: a living language is not obviously flattered by being called anybody's heredaĵo, and the counter-argument is that a hundred and forty years of literature is exactly what the word is for. Heredaĵo also carries the biological sense - what came down to you in the genes - though there hereda as an adjective is commoner: hereda malsano, a hereditary illness.