memoria

Memoria, memoriae, f., is first declension, built on the adjective memor, "mindful". Two idioms carry most of its work: memoriae mandare, "commit to memory", with the dative, and memoria tenere, "remember", literally "hold by memory", with the ablative.

The trap is the temporal sense. Nostra memoria does not mean "our memory" in these contexts; it means "within living memory, in our own time", and post hominum memoriam is "since records began". From there the word slides into the concrete: a memoria is a written record, and in Christian Latin a shrine built over a martyr's relics. Memento, memorial and memoir all come down the same line, as does the sober tag memento mori.